Comparing Gray-Zone Tactics in the Red Sea and the South China Sea

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Comparing Gray-Zone Tactics in the Red Sea and the South China Sea

The Houthis’ activities in the Red Sea and the Chinese actions around Second Thomas Shoal have notable similarities in tactical conduct and adversarial responses.

Comparing Gray-Zone Tactics in the Red Sea and the South China Sea

In this photo provided by the Armed Forces of the Philippines, Philippine resupply vessel Unaizah May 4, right, is hit by Chinese coast guard water cannons causing injuries to multiple crew members as they tried to enter the Second Thomas Shoal in the disputed South China Sea, March 5, 2024.

Credit: Armed Forces of the Philippines via AP

Amid turbulent times at sea, gray-zone tactics have become a preferred tool for actors seeking to advance their interests without resorting to outright military conflict. Essentially, gray-zone tactics mean operating in the murky spectrum between peace and war. Such actions risk eroding the freedom of navigation, a central concept undergirding global economic stability. 

Two recent cases – the Houthis’ activities in the Red Sea, and the Chinese actions around Second Thomas Shoal in the South China Sea – display remarkable similarities when it comes to the operationalization of gray-zone tactics, despite being cut from entirely different contextual cloths. 

A deep-dive analysis of the two cases reveals notable similarities in tactical conduct and adversarial responses, with three critical lessons distilled for the international community to navigate future iterations of such gray-zone tactics out at sea.

The Red Sea Gambit

Based in Yemen, the Houthi movement is a non-state actor that can be classified as an organized armed group with political aspirations. Since hijacking a cargo ship on November 19, 2023, the Houthis have allegedly been targeting Israeli-linked ships to stop Israel from attacking Palestine in Gaza and the West Bank, with this target list further expanding to United States- and United Kingdom-linked ships in March 2024.  

Although the Houthis have utilized military force on commercial vessels, existing international law (including the law of naval warfare) does not apply to conflicts between states and non-state actors. The Houthis’ identity as non-state actors engaging in gray-zone operations makes it tricky for the international community to respond proportionately, despite the threat that their actions pose to regional shipping and maritime security. 

Furthermore, the Houthis continue to spread misinformation and pro-Houthi propaganda through social media platforms, aiming to justify their actions while undermining international support for their adversaries. This tactic seeks to challenge the overarching international narrative by playing up the Houthis’ righteousness in upholding their values and defending their place in the world – consequently portraying any action taken (especially Western responses) as modern-day crusades.

Crucially, the Houthis are strategically targeting a key maritime chokepoint and important shipping lane in the Red Sea – the Bab al-Mandab strait, one that sees 25 percent of the world’s daily shipping pass through it. They have employed missiles, drones, and unmanned vessels against unarmed civilian ships, disrupting global maritime trade and exerting pressure on regional powers to respond. This tactic leverages the geographic vulnerability of the chokepoint to raise the stakes for the international community, amplifying the visibility of the Houthis’ objectives.

The Second Thomas Shoal Blockade

On the other side of the world, there has been an increased frequency of gray-zone tactics employed by the China Coast Guard (CCG) and maritime militia since February 2023, especially around Second Thomas Shoal. China seeks to intercept and block the Philippines’ rotation and resupply missions to BRP Sierra Madre, a rusting hulk grounded on the feature in 1999 and since garrisoned by the Philippine Navy. 

These actions exemplify a different manifestation of gray-zone tactics, which involves the use of lawfare to justify China’s actions, selective interpretations to claim moral high ground, and a persistent presence to demonstrate assertiveness.

China has attempted to utilize lawfare as a justificatory tool by passing the CCG law in late January 2021. This domestic law vested the CCG (and forces under its command) with the authority to enforce jurisdiction in China’s self-declared territorial waters. While there are points of contention between the CCG law and international law, i.e. the United Nations Convention on the Law of the Sea (UNCLOS) – a convention which China has been a party to since 1996 – China has ignored these comparative deviations, while justifying their actions as legitimate under the CCG law’s ambit.

Furthermore, the Philippines has been painted by Chinese media outlets as an aggressor intruding into Chinese territorial waters, with accusations of the former contravening the Declaration on the Conduct of Parties in the South China Sea (DOC). Additionally, Chinese researchers have contended that China maintains the moral high ground by enforcing full compliance with the DOC, and that they had lawfully expelled trespassing Philippine vessels. 

While logical at first glance, this cherry-picking frame omits the fact that the DOC is a non-binding agreement that originated from the Association of Southeast Asian Nations (ASEAN) member-states disputing China’s territorial claims. Such selective interpretations also downplay the violative actions taken by Chinese authorities near Scarborough Shoal since 2012, as well as recent forceful measures taken by Chinese vessels, even while the DOC specifies the use of peaceful means (without the use of force) to resolve such disputes. 

Finally, the CCG has also maintained a near-constant presence around Second Thomas Shoal, with its efforts supplemented by maritime militia vessels manned by “Little Blue Men.” The vessels have employed aggressive actions such as ramming maneuvers and water cannon firings against the Philippines’ resupply vessels, effectively blockading the area and stopping resupply efforts. Given the civilian nature of the Little Blue Men, their actions blur the lines between law enforcement and military action, making it difficult for states to determine the appropriate response. This allows China to demonstrate its assertiveness in defending its South China Sea territorial claims, while avoiding any direct military-on-military engagement.

Parallels in the Gray

While the contexts and motivations behind these two cases differ considerably, there are striking parallels in their use of gray-zone tactics. Both the Houthis and the CCG operate in ambiguous and murky waters by leveraging non-military actors. The Houthis are a non/pseudo-state proxy, whereas China’s maritime militia can either be understood as paramilitary members or civilian fishermen serving similar purposes. Such ambiguity blurs the lines of accountability, making it prohibitively difficult to develop any clear international response. The intentional (or unintentional) weaponization of ambiguity minimizes the risk of escalation, while allowing both groups to advance their political objectives.

Furthermore, both cases show a desire for narrative posturing. While the degree of control differs, both sides have propagated outright falsehoods. While initially claiming to only target Israel/U.S./U.K. linked vessels, the Houthis have also targeted ships with no such connections, such as the vessel STAR IRIS, a Greek-owned, Marshall Islands-flagged ship carrying corn from Brazil to Iran. 

Also, there is irrefutable cherry-picking of beneficial facts, such as China’s highlighting militarization encouraged by the U.S. in the South China (and not its own), as well as labelling the Philippines as an aggressor in the Second Thomas Shoal dispute, despite the area falling within the Philippines’ 200-nautical-mile Exclusive Economic Zone. There is a concerted effort to either manage the narrative in the public domain, or to simply put out an alternate (and often false) narrative to legitimize their actions.

The two cases also involve targeting maritime supply chain(s), albeit at different levels. The Houthis are disrupting international trade and affecting global economic stability to put pressure on Israel and its Western allies over Gaza. The CCG continues to exert a presence in the South China Sea, while disrupting logistical and troop resupply efforts to the rusting BRP Sierra Madre – possibly to prevent reinforcement to the Philippines’ last physical foothold on the Second Thomas Shoal, which is in danger of falling apart due to the harsh conditions out at sea.

‘Fighting’ in the Gray

Gray-zone tactics are employed to confound the adversary. Even if these tactics are recognized for their gray nature, they are designed such that all parties find it difficult to develop an appropriate response. Thereafter, besides recognizing such tactics for their gray overtones, states need to develop flexible and calibrated responses to prevent transgressors from pushing their limits, while continuing to operate below the threshold of war. 

In response to the Houthis, U.S. Defense Secretary Lloyd Austin elucidated the threat of the Houthis’ actions to the sanctity of the rules-based international order. This was followed up with the establishment of Operation Prosperity Guardian, a multinational coalition formed to protect commercial traffic in the Red Sea from Houthi aggression, under the umbrella of Combined Task Force 153. The larger idea behind this is simple – U.S. actions are designed to stall a closing gambit by securitizing the issue. By bringing in 41 states into Prosperity Guardian and playing up the economic and maritime security angles of the Red Sea gambit, the U.S. approach allows for room to escalate or de-escalate when necessary, while also creating a competing frame of reactivity in response to the Houthis’ narrative.

As for the Second Thomas Shoal interceptions, Philippines President Ferdinand Marcos Jr. gathered top officials to discuss the October 2023 collision incident between a Philippines supply ship and a CCG vessel, while simultaneously ordering authorities to conduct a maritime investigation. This was followed up by a direct criticism of China’s escalatory actions, calling out the CCG for its blatant violation and disregard of international law.  

Afterwards, the Philippines started to call on other states to bandwagon and securitize against China’s increasing assertiveness in the South China Sea which has culminated into further cooperation on maritime security ventures with Vietnam, reciprocal maritime access agreements with Japan, and joint naval patrols with Australia in the South China Sea, among others. The larger idea here is similar, with the Philippines’ actions designed to present an opposing narrative to China’s, while bringing in other states with similar security concerns to band together in defense of their respective national interests.

There is a modus operandi in both sides’ responses in the Red Sea and the South China Sea – any reaction starts with an assessment, followed by an open call-out of the transgressor operating in the gray. Afterwards, the state targeted by such gray-zone operations proceeds to develop a narrative to raise the stakes for the international community, which brings in like-minded states with similar interests and fundamental security considerations at stake, into the equation.

Lessons in Navigating the Gray Zone

While the securitization actions taken above are contextualized to the gray-zone tactics employed, a detailed analysis of the two cases’ parallels reveal further insights in navigating gray-zone challenges.

First, the ambiguity of gray-zone tactics underscores the pressing need for a coordinated international response across different levels, institutions, and actors. Fragmentation and unilateral responses significantly weaken international efforts, and this logic applies even for powerful states. The intricacy of gray-zone tactics require the pooling of resources and ideas amongst different players with similar stakes. 

Furthermore, even as states work together to develop effective strategies for deterring and countering these tactics, what is perhaps critical to the success of such responses is the nuance to how these collaborative efforts come to fruition. In the case of Operation Prosperity Guardian, operations may have started off on the wrong foot as a U.S.-led response could have strengthened the Houthis’ narrative of “the West” continuing an age-old campaign of aggression against Middle East nations. Likewise, the Philippines’ engagements with most of the Quadrilateral Security Dialogue partners (Australia, Japan, the U.S., etc.) on South China Sea issues could result in further alienation vis-à-vis China, further weakening the significance of its response to Chinese actions in the Second Thomas Shoal. 

Simply put, the frame matters for a multitude of reasons, from the legitimacy of the response to the adversary’s willingness to engage in diplomatic channels to resolve such tensions. The selected frame around Prosperity Guardian could have been refined to avoid associations with such inflammatory narratives.

Second, the growing importance of maritime chokepoints to the international community necessitates stronger international cooperation on maritime security. States, both big and small, need to recognize the importance of investing in maritime security, and to strengthen existing mechanisms to improve situational awareness and enhance common protocols. This process refers not only to interactions among the decision-making bodies of regional and global powers, but also broadened cooperation and capacity-building with local authorities and the commercial shipping community. 

Strengthening maritime security frameworks to allow authorities and stakeholders to expose gray-zone tactics by putting out factually correct narratives is important in shaping public perception, and ensuring maritime legislation is updated to hold actors accountable is crucial to deter future violations. Efforts to clarify and strengthen existing legal frameworks, such as the recent revision of the Newport Manual on the Law of Naval Warfare to factor in developments such as the use of autonomous vessels, are critical in safeguarding the relevance and applicability of existing international rules governing interactions out at sea. 

Lastly, stakeholders need to return to the soft underbelly of such gray-zone tactics by recognizing that such issues often stem from deeper political and socioeconomic grievances. The roots of Houthis’ actions can be traced to the Iran-Israel proxy war, with Iran supporting multiple proxies (including the Houthis) with the resources to threaten Israel, while Israel had been intercepting suspicious vessels to prevent Iranian supply of arms to these proxies. Israel’s retaliatory responses to the October 2023 Hamas attacks can be understood as the spark that led to the Houthis targeting vessels in the Red Sea. 

As for China, its motivation can be traced back to the Century of Humiliation, which made the perceived loss of sovereignty an extremely sensitive issue. It is etched into Chinese collective memory that the maritime area enclosed by the nine-dashed line in the South China Sea is China’s alone, based on historical claims. While China has displayed significant resistance to any external attempts to contravene these claims, protecting the sanctity of the rules-based international order should remain a priority for all states, especially UNCLOS signatories. As such, states need to lay the groundwork for long-term stability by engaging in diplomacy and developmental initiatives to address these underlying motivations, and to reduce the appeal for actors to resort to gray-zone tactics.


The Houthis’ activities in the Red Sea and China’s maneuvers near Second Thomas Shoal showcase the diverse ways gray-zone tactics are employed in the 21st century. While the actors and contexts differ, these cases highlight the need for a nuanced and coordinated response from the international community to counter these challenges and maintain a peaceful and stable global order. By fostering unified responses, investing in maritime security, strengthening international law, and addressing underlying issues, the international community can better navigate the murky waters of gray-zone tactics and chart a course toward brighter seas.