In its second provocative Freedom of Navigation operation in the South China Sea this year, the US Navy sent two guided missile destroyers yesterday—the USS Spruance and USS Preble—within the 12 nautical mile territorial limit claimed by China around Mischief Reef in the Spratly island group.

The naval operation coincided with the beginning of trade talks between the US and China this week ahead of a March 1 deadline by US President Trump for a deal to avert even more aggressive US trade war measures against China. The intervention of the two destroyers is designed to send a menacing message to Beijing that the US intends to step up its confrontation on all fronts unless China bows to its demands.

Naval spokesman Commander Clay Doss told CNN that the navy carried out the operation “to challenge excessive [Chinese] maritime claims and preserve access to the waterways as governed by international law.” China has never threatened access by international shipping to the South China Sea.

Admiral John Richardson, chief of naval operations, told reporters earlier this month that China was placing military hardware on the islets under its control in the South China Sea. “There’s been sort of a steady increase,” he said. “The weapons systems have been getting increasingly sophisticated so it’s something we’re watching very closely.”

In reality, China’s expansion of facilities in the South China Sea is in response to Washington’s increasingly aggressive challenges to China’s territorial claims and to the US military build-up in Asia, firstly under President Obama and now Trump. The South China Sea is adjacent to major Chinese military bases, including its nuclear submarine pens on Hainan Island.

Chinese Foreign Ministry spokeswoman Hua Chunying yesterday condemned the latest US naval intrusion. She expressed China’s “strong dissatisfaction and resolute opposition” and called on the US to “immediately stop its provocative actions.”

Hua said: “The relevant actions of the US warships violated Chinese sovereignty, and undermined peace, security and order in the relevant sea areas.” She declared that China had “indisputable sovereignty over islands in the South China Sea, including the Second Thomas Shoal, Mischief Reef, and the adjacent waters.”

The repeated US military provocations in waters near the Chinese mainland are fuelling calls for tougher counter-measures.

“If the US warships break into Chinese waters again, I suggest that two warships should be sent: one to stop it, and another one to ram it,” Senior Colonel Dai Xu told a forum in December organised by the hawkish Global Times newspaper. “In our territorial waters, we won’t allow US warships to create disturbance.”

Last September, the USS Decatur sailed within 12 nautical miles of the Gaven and Johnson reefs controlled by China in the Spratly Islands. In a bid to ward off the US warship, a Chinese destroyer came within 45 metres of the USS Decatur in a manoeuvre denounced by the US navy as unsafe and unprofessional.

The incident was another indication as to how tense the situation in the South China Sea has become.

Last month’s naval provocation by the US also took place at the start of trade talks with China. On January 7, the destroyer USS McCampbell intruded within the 12 nautical mile limit around the Paracel Islands in South China Sea. On the same day, US and Chinese negotiators began three days of talks in Beijing to defuse the mounting trade war.

US-China tensions in the South China Sea have escalated dramatically since the Obama administration directly intervened in territorial disputes between China and neighbouring South East Asian countries that had previously been regarded as low-key regional matters.

US Secretary of State Hillary Clinton provocatively told a regional forum of the Association of South East Asian Nations (ASEAN) in 2010 that the US “was back in Asia to stay,” had a “national interest” in ensuring freedom of navigation in the South China Sea and offered to become involved in the territorial disputes.

The Obama administration launched the first freedom of navigation operations in the South China Sea and gave strong backing to the decision by the Philippines to challenged China’s maritime claims at the International Tribunal for the Law of the Sea in the Hague. The US itself was in no position to challenge Chinese claims firstly because it was not a party to the territorial disputes, and secondly, because it has not ratified the UN Convention on the Law of the Sea. The court ruling in 2016 ruled against the existence of territorial waters in the South China Sea, but did not adjudicate on the sovereignty of the disputed islands.

Obama’s aggressive challenge to China in the South China Sea was part of a far broader confrontation—diplomatically, economically and militarily—known as the “pivot to Asia.” The US exploited issues such as the South China Sea to drive a wedge between China and its neighbours, strengthened diplomatic and military ties throughout the region, sought to isolate China economically and expanded US military forces throughout the Indo-Pacific.

Trump has taken up where Obama left off, threatening a full-blown trade war and making further preparations for military conflict. The political establishment in Washington has fallen into line with these threats and provocations in a bid to ensure that China, now the world’s second largest economy, never challenges US global domination.

The US is also pushing for its allies to become actively involved in naval provocations in the South China Sea. Last August the British navy sent the HMS Albion close to the Paracel group in its first freedom of navigation operation. In January, the frigate HMS Argyll carried out the first joint US-British exercise in the South China Sea with the USS McCampbell “to address common security priorities.”

Yesterday, British Defence Secretary Gavin Williamson announced that the aircraft-carrier Queen Elizabeth, with two squadrons of F-35 stealth fighters, will be sent into disputed waters in the Pacific. In his speech, Williamson declared that Western allies must be prepared to “use hard power to support our interests,” and failing to intervene against aggressive foreign powers “risks our nation being seen as little more than a paper tiger.”

Such reckless actions by the US and its allies risk an incident, whether accidental or deliberate, that triggers a devastating war between nuclear armed powers.