China cranks South China Sea buildup while Iran consumes US

China’s renewed land reclamation at Antelope Reef comes as the ongoing US-Israel-Iran War draws significant US military assets into the Middle East, raising questions over whether shifting US force posture is opening strategic space in the South China Sea.

This month, The Wall Street Journal (WSJ) reported that China has stepped up land reclamation at Antelope Reef in the disputed South China Sea, satellite imagery shows, underscoring an effort to consolidate maritime claims and reshape the strategic balance in a potential Taiwan-linked conflict.

The activity, reported in January 2026 and visible in European Space Agency Sentinel-2 images, began in October and involves dredging at multiple points along the reef’s lagoon, expanding land around an existing outpost and port facility.

Located in the western Paracel Islands, roughly 400 kilometers east of Vietnam and 281 kilometers from China’s Hainan-based Sanya naval hub, the reef sits in a vital trade corridor carrying about one-third of global maritime commerce.

The buildup fits China’s broader strategy of enhancing surveillance, electronic warfare, and anti-access/area denial capabilities (A2/AD) across dispersed artificial islands, enabling persistent monitoring and complicating adversary operations.

Although US assessments suggest such outposts are vulnerable to precision strikes, missile shortages, rapid Chinese runway repair capabilities and expanding electronic warfare capabilities could limit US effectiveness. The expansion also highlights China’s aim to deny US forces information and operational options rather than rely solely on defending fixed positions.

The ongoing US-Israel-Iran conflict is likely motivating China to speed up its island-building in the South China Sea as key US forces in the Pacific have been moved to the Middle East, opening a window of opportunity for China.

That shift in focus is reflected in both force deployments and surveillance activity across the Indo-Pacific. The US Naval Institute (USNI) fleet tracker shows that as of March 30, 2026, the US has redeployed the USS Abraham Lincoln carrier strike group (CSG) from the South China Sea and is now in the Middle East, with the USS George Washington (CSG) to join the USS Abraham Lincoln CSG, underway from its homeport of Yokosuka, Japan.

Apart from those carrier redeployments, the 31st US Marine Expeditionary Unit (MEU) has already been deployed to the Middle East, with the formation built around the USS Tripoli amphibious assault ship. In addition, the 11th MEU, centered on the USS Boxer, is also en route to the region from its homeport in San Diego, California.

The redeployment of the USS Abraham Lincoln and USS George Washington CSGs to the Middle East could leave the USS Theodore Roosevelt CSG as the only US carrier force in the region.

With only one US CSG in the Pacific, the US might be facing a serious carrier gap, weakening its ability to respond to multiple hotspots, including the Korean Peninsula, the Taiwan Strait, and the South China Sea.

Additionally, moving two US MEUs from the Pacific to the Middle East could limit US operational flexibility in the First Island Chain. This region depends heavily on dispersed marine littoral operations, amphibious mobility, and forward-based aircraft, such as fighter jets, stationed on amphibious assault ships.

Furthermore, the South China Morning Post (SCMP) reported in March 2026 that US reconnaissance flights in the South China Sea dropped by 30%, citing the South China Sea Strategic Situation Probing Initiative (SCSPI), a Chinese think tank.

According to the SCSPI, there were only 72 US reconnaissance flights over the South China Sea in February 2026, a sharp drop from 102 flights from December 2025 to January 2026.

While SCMP and SCSPI did not specify the cause, the drop coincides with the US focus on the Middle East and efforts to create favorable conditions for a planned meeting between US President Donald Trump and Chinese President Xi Jinping.

With the US facing a potential two-front problem in the Middle East and the Indo-Pacific, China appears to have used the situation to scale up construction at Antelope Reef.

According to the Asia Maritime Transparency Initiative (AMTI) report from March 2026, China’s swift construction efforts at Antelope Reef may transform it into China’s largest occupied feature in the Paracel Islands, and potentially in the entire South China Sea.

Using commercial satellite images from Vantor, AMTI estimated that the reclaimed land at Antelope Reef is roughly 6.11 square kilometers. The report also states that Woody Island in the Paracels, which hosts an air and naval base, and Sansha City cover about 3.44 square kilometers. Meanwhile, AMTI says Mischief Reef in the South China Sea spans 6.16 square kilometers, almost identical to Antelope Reef’s current size.

AMTI states that Antelope Reef could now support a 2,743-meter runway similar to those already built by China at Woody Island, Mischief Reef, Subi Reef and Fiery Cross Reef. It notes that the northwestern side of the new landmass at Antelope, which extends more than 16,795 meters, has been shaped with a noticeably straight outer edge ideal for an airstrip.

However, other claimants in the South China Sea may not be taking chances. For instance, John Pollock and Damien Symon note in a March 2026 Chatham House article that Vietnam has rapidly expanded reclamation work across all 21 of its controlled features in the Spratly Islands, framing this as a response to China’s own island-building activities.

Citing March 2025 data from AMTI, Pollock and Symon state that Vietnam has dredged approximately 13.4 square kilometers of coral reef since 2022; the same data shows China dredged about 18.8 square kilometers.

They also mention that small concrete outposts on several of Vietnam’s occupied features have been supplemented by large-scale artificial islands, with munition storage facilities and artillery and rocket launcher positions spotted.

Pollock and Symon warn that this has effectively opened a “Pandora’s box” of competitive island-building across the region, as claimants such as Vietnam scramble to fortify their own outposts.

If those trends persist, China’s buildup at Antelope Reef — enabled in part by reduced US presence — could lock in a more militarized South China Sea, accelerate regional fortification, and raise the cost of restoring US operational dominance.