Late this week, the US State Department accused China of escalating its coercive actions against Vietnam in the South China Sea.

A spokesman said the US is "deeply concerned" China is continuing its interference with Vietnam's longstanding oil and gas activities in the Vietnamese Exclusive Economic Zone (EEZ) claim.

"This calls into serious question China’s commitment, including in the ASEAN-China Declaration on the Conduct of Parties in the South China Sea, to the peaceful resolution of maritime disputes," the statement said.

Military officers of the Vietnamese Navy's Second Regional Command signalling territorial claims. Source: Viet Nam News

This week the National Interest described in detail the worsening situation in a piece aptly titled South China Sea Showdown: China vs. Vietnam (Round 2).

The report described a Chinese survey vessel dispatched inside the Vietnam claimed EEZ accompanied by Chinese Coast Guard military vessels:

The Haiyang Dizhi 8, a survey vessel belonging to a Chinese government-run corporation, began surveying a large swath of seabed on 3 July northeast of Vanguard Bank, which falls within Vietnam’s exclusive economic zone. The ship has been escorted by other vessels, including from the China Coast Guard and maritime militia. At the same time, China Coast Guard ships have been harassing Vietnamese drilling operations to the south.

Western analysts see Beijing's expansion in regional waters as part of a broader campaign of natural resource exploitation, with the ultimate goal of forcing rival countries into 'joint exploration' partnerships, even in undisputed waters.

According to the report, the current crisis is the most serious tensions have been between China and US ally Vietnam in years:

Chinese incursions into Vietnam’s EEZ are by no means a new phenomenon. The most serious recent incident occurred in 2014, when China deployed an oil rig into Vietnam’s EEZ, sparking a diplomatic crisis between the two neighbors. The current situation near Vanguard Bank, however, represents a more serious challenge on several levels.

Early this week the US State Department issued a comprehensive press report alleging "China’s interference with oil and gas activities in the South China Sea (SCS), including Vietnam’s long-standing exploration and production activities."

China has repeatedly sent survey vessels into waters outside its recognized EEZ.

It condemned Beijing's "repeated provocative actions aimed at the offshore oil and gas development of other claimant states," which the statement further described as threatening "regional energy security and undermine the free and open Indo-Pacific energy market."