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South China Sea: PRC grey-zone pressure persists as Manila hardens posture and widens partnerships

Time window: Last 7 days · Audience: General analyst · Type: Situation report · DTG: 2026-07-03 10:16Z · Overall confidence: MEDIUM

BLUF

China is very likely sustaining coercive pressure on Philippine-held features through the China Coast Guard and Chinese Maritime Militia, while the Philippines hardens basing and air-maritime capabilities and deepens cooperation with Vietnam, Japan and the United States. The near-term risk of a non-lethal maritime incident at Ayungin Shoal remains elevated.

Executive summary

Open-source reporting indicates a persistent pattern of China Coast Guard aggressive manoeuvres, militia swarming and a blockade posture at Ayungin Shoal against Philippine vessels. Manila is responding by planning upgrades to strategic island bases and acquiring long-range patrol aircraft and helicopters, and by tightening security ties with Vietnam and Japan alongside its decades-old alliance with the United States. Diplomatically and legally, the Philippines continues to anchor its position in the 2016 arbitral award and UNCLOS, and is being urged to advance a high-seas marine protected area under the BBNJ treaty framework. These trajectories point to steady grey-zone friction with a roughly even chance of a non-lethal incident in the near term, and an uptick in joint maritime activities with partners over the coming months.

Change from previous assessment

Since the 2 July brief, new reporting in scope details Philippine plans to upgrade contested-island bases and to acquire long-range patrol aircraft and helicopters, and shows Manila consolidating maritime partnerships with Vietnam and Japan while maintaining its alliance with the United States. This update adds an assessment on the likely growth of BBNJ-driven legal-diplomatic activism. Confidence remains medium; no new claims directly addressed the prior note’s reported pattern around Huangyan Island, so the focus here shifts to Philippine capability and partnership trajectories.

Key judgments

1. China is very likely sustaining a coordinated grey-zone pressure campaign against the Philippines in the South China Sea, using Chinese Maritime Militia swarms, aggressive China Coast Guard manoeuvres, and a blockade posture at Ayungin Shoal. (Confidence: high · REPORTED)

• I&W: Fresh massing of Chinese Maritime Militia or China Coast Guard interdiction patterns within 12 nautical miles of Ayungin Shoal documented by Manila or independent monitoring feeds (0-14 days)
• I&W: Sustained drawdown in China Coast Guard and militia presence around Ayungin Shoal visible on commercial satellite imagery or AIS (0-14 days)

2. The Philippines is very likely hardening its posture through planned upgrades to strategic bases on contested islands and new long-range patrol aircraft and helicopter acquisitions, with Thitu Island remaining a focal base. (Confidence: high · REPORTED)

• I&W: Announcement of contract awards or delivery schedules for long-range patrol aircraft or helicopters (1-3 months)
• I&W: Official delay or cancellation of the island base upgrade programme (1-3 months)

3. Manila is likely to increase joint maritime activities with partners, having elevated ties with Japan and Vietnam and agreed to enhance coast guard cooperation with Hanoi, while retaining its mutual defence treaty with the United States and benefitting from continued freedom of navigation operations. (Confidence: medium · ASSESSED)

• I&W: Public notice of joint Philippines, Vietnam coast guard patrols or exercises in the South China Sea (1-3 months)
• I&W: Postponement or shelving of planned bilateral or trilateral maritime drills after Chinese protests (1-3 months)

4. Beijing will very likely continue to reject the 2016 arbitral award and advance its nine-dash line narrative while conducting activities such as research-vessel seabed mapping within the Philippine exclusive economic zone, ensuring legal friction persists. (Confidence: medium · ASSESSED)

• I&W: New PRC statements restating non-acceptance of the 2016 award or fresh deployments of state research vessels into the Philippine exclusive economic zone (1-3 months)
• I&W: Joint PRC, Philippine communiqué signalling discussions framed around the arbitral ruling or a pause in PRC seabed surveys (1-3 months)

5. There is a roughly even chance of a non-lethal collision or disabling incident involving a Philippine government vessel at Ayungin Shoal in the near term, given the China Coast Guard's aggressive manoeuvres, the militia swarming approach, and a blockade posture. (Confidence: medium · ASSESSED)

• I&W: Official Manila reporting of ramming, blocking, or collision incidents near Ayungin Shoal (0-14 days)
• I&W: Announcement of temporary stand-down measures or confidence-building protocols specific to interactions at Ayungin Shoal (0-14 days)

6. Legal-diplomatic activism by Manila on high-seas conservation is likely to build, including steps toward proposing a marine protected area under the BBNJ treaty, to rally support and shape norms in the South China Sea. (Confidence: medium · ASSESSED)

• I&W: Philippine interagency announcement of intent to table a BBNJ marine protected area proposal covering high-seas areas of the South China Sea (1-3 months)
• I&W: Public pushback within the Philippine government against sponsoring a high-seas protected area under BBNJ (1-3 months)

Outlook & scenarios

Baseline: protracted grey-zone friction without fatalities (60%)

China Coast Guard harassment, militia swarming and the blockade posture at Ayungin Shoal continue, while Manila proceeds with base upgrades and procurement of long-range patrol aircraft and helicopters. Encounters remain mostly non-lethal but hazardous, with frequent near-collisions and equipment damage claims.

Incident-driven surge in allied presence (30%)

A disabling incident or collision at Ayungin Shoal prompts rapid consultations under the Philippines, United States mutual defence framework and a visible uptick in allied naval and coast guard activity, alongside additional freedom of navigation operations. Beijing protests and raises deployments, increasing operational density and miscalculation risk.

Lawfare-led pressure campaign (35%)

Manila prioritises legal-diplomatic tools by moving toward a BBNJ high-seas marine protected area proposal and expanding coast guard cooperation with Vietnam under an enhanced strategic partnership, while deepening ties with Japan. Beijing rejects the arbitral award narrative and counters diplomatically; at sea, interactions remain tense but calibrated to avoid major incidents.

Recommendations

1. Maintain a daily OSINT and commercial satellite/AIS watch on Ayungin Shoal to track China Coast Guard and militia massing patterns and intercept geometries; flag any trend toward blocking formations or close-quarter manoeuvring.
2. Map and track the Philippines’ basing and procurement timelines by monitoring defence statements, contracting notices and delivery schedules for long-range patrol aircraft and helicopters; identify windows when capability gains will alter on-water detection and response.
3. Build a vessel-profile library for PRC state research ships operating in the Philippine exclusive economic zone to support rapid attribution of seabed-mapping sorties and provide timely legal-diplomatic context.
4. Establish a standing indicator set for partner activities: monitor official notices of Philippines, Vietnam coast guard exercises and announcements tied to the Japan, Philippines comprehensive strategic partnership, as well as recurring freedom of navigation operations.
5. Prepare incident-response analytic products keyed to a non-lethal collision scenario at Ayungin Shoal, outlining likely diplomatic steps under the Philippines, United States mutual defence framework and potential PRC counter-messaging.

Confidence & uncertainty

Overall confidence is medium. Several key elements rest on multiple, mutually reinforcing major-media reports and official statements, including China Coast Guard aggression, Chinese Maritime Militia swarming, a blockade posture at Ayungin Shoal, and Manila’s basing and acquisition plans. Assessments about the trajectory of partnerships and legal-diplomatic initiatives extend beyond direct reporting, and some legal-context claims vary in precision and date references, which tempers confidence. The mix of high-confidence reporting for core behaviours and medium-confidence sources for forward-looking inferences supports a medium headline confidence.

Alternative analysis (red cell)

Several key judgments rely heavily on declaratory statements or single‑thread reporting without convergent, high‑admiralty operational evidence. An alternative, defensible assessment is that PRC presence in the area could reflect episodic fishing and isolated coast guard enforcement rather than a unified, centrally directed grey‑zone campaign; Manila’s capability upgrades and partner cooperation remain largely declarative pending procurement, imagery, and operational records; and Philippine BBNJ activism is aspirational absent clear ratification and diplomatic buy‑in. Resolving these issues requires multi‑source technical corroboration and official documentary evidence.

Intelligence gaps

• [EEI 1.1 · PARTIAL] Number, class, and position (time-stamped) of Chinese Coast Guard (CCG), People’s Armed Forces Maritime Militia (PAFMM), and other PRC paramilitary/auxiliary vessels inside Philippine-claimed EEZ or within 12 nautical miles of Philippine-occupied features (e.g., Scarborough Shoal, Second Thomas/Ayungin Shoal, and other named features). Recommended collection: maritime/AIS
• [EEI 1.2 · PARTIAL] Observed maneuvers or posture indicating hostile action: vessel-to-vessel blocking/contact, use of water cannons, boarding attempts, formation maneuvers to interdict Philippine vessels, or sustained stationing near Philippine resupply/relief routes. Recommended collection: imagery/satellite
• [EEI 1.3 · PARTIAL] Incidents of Philippine vessels (coast guard, navy, supply boats, civilian fishing vessels) being ordered to alter course, detained, chased, or physically impeded — with time, location, involved units, and damage/injuries if any. Recommended collection: open-source/official statements
• [EEI 1.4 · UNCOVERED] Abrupt changes to vessel identification behavior: AIS transponder deactivations, spoofing, or mismatches between flagged identity and observed equipment/markings among PRC maritime law-enforcement or militia vessels operating near Philippine claims. Recommended collection: maritime/AIS
• [EEI 2.1 · UNCOVERED] Issued directives, patrol orders, or internal guidance from PRC Central Military Commission, PLAN, CCG, or provincial maritime authorities that specify objectives, geographic limits, patrol tempos, or escalation thresholds for operations near Philippine-claimed features. Recommended collection: signals/communications
• [EEI 2.2 · UNCOVERED] Public declarations, maritime notices, or newly published 'maritime safety' or exclusion zones, with effective dates and coordinates, issued by Chinese authorities that could be used to justify interdiction or exclusion of Philippine activity. Recommended collection: open-source/official statements
• [EEI 2.3 · PARTIAL] Evidence of mobilization orders, tasking lists, or logistics planning for Maritime Militia units (vessel requisitions, local fisheries bureau instructions, fuel/resupply manifests) indicating intent to employ militia alongside CCG/PLAN assets. Recommended collection: HUMINT/defense
• [EEI 3.1 · PARTIAL] Deployment and movement of Philippine Coast Guard and Navy vessels (class, location, on-station times) and scheduled or unscheduled escort/resupply missions to occupied features. Recommended collection: military/AIS
• [EEI 3.2 · PARTIAL] Air component activity: number and frequency of Philippine air patrol sorties, maritime domain awareness flights, and air-to-surface or maritime strike assets placed on alert or redeployed toward contested areas. Recommended collection: imagery/satellite
• [EEI 3.3 · PARTIAL] Requests for diplomatic, intelligence, or military assistance from allies (e.g., U.S., Australia, Japan) including notifications of planned joint patrols, port calls, or freedom of navigation operations with dates and participating units. Recommended collection: open-source/official statements
• [EEI 3.4 · UNCOVERED] Changes to Philippine rules of engagement, emergency law measures, mobilization orders, or civil advisories (evacuations, fishing bans) that alter civilian or military behavior in contested maritime zones. Recommended collection: open-source/official statements

Cited sources

[1] rappler.com · [OPINION] Why China won't just leave out the Philippines (B) · sha256:ff58f1de45ba [2] Newsweek · U.S. ally Philippines plans bases on front lines of South China Sea dispute (A) · sha256:bbfe12aae835 [3] rappler.com · [OPINION] Marcos faces delicate balancing act as he looks to Russia for oil (B) · sha256:8419a573eb90 [4] Wikipedia · Territorial disputes in the South China Sea (F) · sha256:9bd4070987a2 [5] rappler.com · FACT CHECK: International law backs PH claim to the West Philippine Sea (A) · sha256:3570698a74a9 [6] rappler.com · This research museum takes a snapshot of what's in Philippine waters (B) · sha256:63400f9a9a01

Source content hashes were computed at collection time; the cited text is preserved unmodified for the life of this product.

Red cell review: PARTIAL DISSENT

TLP:CLEAR