The U.S. flew two b-52s along a route that took them over a disputed island chain and deep into China's newly established air defense zone, reports the WSJ.

Japan released a statement saying the new zone was another obvious attempt to co-opt the disputed island chain, known as the Diaoyus in China, and Senkakus in Japan.

"I am strongly concerned as it is a profoundly dangerous act that may cause unintended consequences," Prime Minister Shinzo Abe told his parliament.

The U.S. quickly backed Japan, saying it would not honor Chinese demands for advanced notice and flight plans.

The WSJ has more:

The planes flew out of Guam and entered the new Chinese Air Defense Identification Zone at about 7 p.m. Washington time Monday, according to a U.S. official.

The flight of the B-52s, based at Anderson Air Force Base in Guam, were part of a long planned exercise called Coral Lightening. The bombers were not armed and were not accompanied by escort planes.

China's assertions over the isles — administered by Japan since 1972 — have become increasingly aggressive this year. On Oct. 15, David Cenciotti of the Aviationist noted that Japan scrambled fighters against Chinese (and Russian) air incursions "185 times in the last three months."

Agence France Presse notes China's new statement about interceptions:

"Tokyo is hypocritical and impudent in its complaint with Beijing," said an editorial in the Global Times newspaper, which is close to China's ruling Communist Party.

"If Japan sends warplanes to 'intercept' China's jet fighters, Beijing's armed forces will be bound to adopt defensive emergency measures," it said.

American B-52s have been in flight for nearly 60 years, and carry everything from drones to nukes. It's one of the most reliable bombers in U.S. history.

Conversely, a posting by Chinese news site Xinhua places the blame for instigation predictably at the feet of the U.S., saying, "Washington and Tokyo accused China of undermining the stability of the Asia-Pacific region. But in fact, it is Washington and Tokyo that pose threat to the peace and stability in the region."

China has also recently dispatched a diesel aircraft carrier and two destroyers out to the South China sea, likely to further assert their claim.