Gray Zone Tactics Playbook: Blocking

Blocking is the act of physically impeding the passage of a ship to its destination—a form of maritime area denial.
Gaute Friis | JULY 19, 2023
Gray Zone Tactics Playbook: Blocking
CCG 5201 blocks the path of BRP Malapascua, forcing it to abort its planned patrol of the Second Thomas Shoal after a 30 minute stand-off, April 26, 2023 (Source: BBC)

Gaute Friis




Blocking is a form of bow-crossing meant to physically impede the passage of another ship to its destination. Blocking is typically used by Chinese ships to hinder other countries from resupplying or reinforcing their outposts in the South China Sea.

Distinct from other forms of bow-crossing, blocking is used for area denial rather than operations disruption and will often result in more protracted stand-offs. China uses this tactic to assert its claims of jurisdiction as well as to prevent certain activities--most notably the reinforcement of other claimants' existing Spratly Island outposts.

One such blocking maneuver occurred on April 26th, 2023, when China Coast Guard (CCG) ship 5201 blocked the path of the Philippine Coast Guard (PCG) patrol vessel BRP Malapascua. This forced the much smaller PCG ship to abort its planned route to the entrance of Second Thomas (Ayungin) Shoal during a resupply mission to the Philippines' outpost aboard BRP Sierra Madre

China routinely prevents the entry of Philippine ships into the interior of Second Thomas Shoal as a cornerstone of its strategy to prevent the rusting outpost from being repaired or replaced until it breaks up or otherwise becomes uninhabitable. For nearly a decade it has allowed only small wooden boats carrying food and replacement troops to pass through its blockade.

Resupply boat brings food and replacement troops to the Philippine outpost aboard BRP Sierra Madre, Second Thomas Shoal, 21 June 2022. Credit: Inquirer/ Marianne Bermudez

Other examples: 

On September 19, 2019, also near Second Thomas Shoal, a CCG ship blocked Philippine civilian vessels while they were conducting a resupply mission to the BRP Sierra Madre.

On November 13, 2015, about 13 nautical miles from Subi Reef, CCG cutters 35115 and 2305 blocked the path of a Vietnamese replenishment ship heading towards the Vietnamese outpost on Southwest Cay, forcing the ship to find a different route to its destination. PLA Navy Type 072A landing ship 995 later blocked the ship's path again, this time brandishing small arms and firing a warning shot.

See the rest of the playbook here.

Gaute Friis

Gaute is a Defense Innovation Scholar at Stanford's Gordian Knot Center for National Security Innovation.

More Articles

Gray Zone Tactics Playbook: Pretext to Escalate
While other countries treat maritime incidents as crises to be deescalated, Beijing seizes upon them as pretext for calculated escalations, by which it means to reset the board in its favor.
It's time for U.S. troops to visit Thitu Island
The U.S. has long kept its distance from the occupied South China Sea features, holding to the notion that keeping the status quo was crucial to avoiding conflict. Unfortunately, Beijing interpreted this reticence as weakness and gutted that status quo, while America's treaty ally, the Philippines, bore the brunt of China's gray-zone expansionism. The journey toward reclaiming the initiative can start with a single, modest step--sending U.S. & Philippine military doctors and engineers to Thitu Island.
China has been surveying Malaysia's waters for over a month
On 21 June 2023, China's hydrographic research vessel Haiyang Dizhi Ba Hao (also known as Haiyang Dizhi 8, or HD8) began an extensive survey at Luconia Shoals on Malaysia's continental shelf--a project that has continued for over a month so far.
sealight logo
Contact Us