The United States has sent a clear message to China not to overstep its territorial ambitions in the East China Sea by flying a pair of B-52 nuclear bombers through air-space disputed by Japan and China.
The flights by the two unarmed aircraft came three days after Beijing unilaterally declared an aerial identification zone over a large area that includes the Senkaku islands, known as Diayou in China - the subject of a bitter territorial feud with Japan.
The two US aircraft did not identify themselves as they entered China's self-declared Air Defence Identification Zone, the Pentagon said yesterday, pointedly referring to the disputed islands by their Japanese name.
"We have continued to follow our normal procedures, which include not filing flight plans, not radioing ahead and not registering our frequencies," said spokesman Colonel Steve Warren.
The White House spelled out the significance of the B-52 flights, publicly rejecting the Chinese zone and urging Beijing to focus on diplomatic means to resolve the dispute.
"The policy announced by the Chinese over the weekend is unnecessarily inflammatory," said White House spokesman Josh Earnest. "These are the kinds of differences that should not be addressed with threats or inflammatory language, but rather can and should be resolved diplomatically."
A Chinese Defence Ministry statement last night said the planes were detected and monitored as they flew through the zone for two hours and 22 minutes. It said all aircraft flying through the zone would be monitored and asserted that China had the ability to control the airspace.
It didn't mention its threat to act against noncompliant aircraft included in last weekend's announcement.
The ministry had previously said it had lodged protests with the US and Japanese embassies in Beijing over the two nations' criticism of the zone.
Beijing sent its sole aircraft carrier for its first training mission into the South China Sea yesterday, amid maritime disputes with the Philippines and other neighbours.
China's approach to the disputed islands has been increasingly bellicose since Xi Jinping, the new President of China, took office in March.
Regional analysts said declaration of the zone was seen partly as a move by Xi to build his leadership credentials with a domestic audience, but also as part of desire to test the resolve of the US and its regional allies.
Officially the US is neutral about the disputed island chain, however the US would defend them under its commitments in Article 5 of the US-Japan Security Treaty, said Nicholas Szechenyi, a senior fellow at the Centre for Strategic and International Studies.
"The US has stated repeatedly that any attempt to change the status quo unilaterally or through coercive means would be unacceptable. The B-52 flights were intended to reflect that."
The bombers flew out of the US territory of Guam on Tuesday. US officials claimed the flights were long-planned and not in direct reaction to China's latest declaration.
The Chinese announcement of the zone was immediately disputed at the weekend by South Korea as well as Japan, which summoned Chinese diplomats to protest. Tokyo ordered two of its biggest airlines, ANA and Japan Airlines, to stop filing flight plans with the Chinese as a demonstration of Japan's disapproval.
The dispute between China and Japan over the Senkakus, which sit atop potentially vast oil and gas reserves, has simmered for decades, but heated up in September 2012 when Japan nationalised three of the islands.
The move provoked fury in Beijing and a series of cat and mouse games between Chinese and Japanese ships and aircraft that analysts warned carried the serious risk of sparking an accidental conflagration.
China's unilaterally declared zone overlaps with a Japanese zone that was declared in the 1960s and over which the Japanese keep records of foreign incursions - a practice which China was expected to mirror as part of its desire to get the islands internationally recognised as "disputed".
The B-52 flights were a rare display of intent by the US, which used a similar tactic last March over South Korea territory as a signal to the North not to overstep its mark.
Using a similar tactic against China has potentially far greater consequences, drawing reminders of the far more serious Taiwan Straits crisis of March 1996.