A dispute over a small island group heated up considerably this morning after China sent a government aircraft into Japanese airspace to surveil the uninhabited Senkaku Islands.  Japan scrambled F-15s to confront the plane, which left without incident, but the two nations have traded diplomatic shots over the incident, CNN reports:

Japan has filed a protest with China over the incursion:

Japan lodged a protest against Beijing today, after a Chinese government airplane was spotted near the disputed Senkaku Islands, prompting Tokyo to scramble F-15 fighter jets, Chief Cabinet Secretary Osamu Fujimura said.

The Ministry of Defense said the incident involving a Chinese Oceanic Administration aircraft marked the first time a Chinese plane violated Japanese airspace, and threatened to escalate already tense Sino-Japanese relations, just days before a crucial Lower House election, where the conservative Liberal Democratic Party is expected to take back power.

The fixed-wing plane, marked “CMS” was spotted near Uotsuri Island in the East China Sea at 11:06 a.m. local time, prompting Japan’s Air Self Defense Force to dispatch eight F-15 jets, according to the Ministry of Defense. Patrol boats in waters below warned the pilot to “stay out of our air space” over the radio, but the crew responded “this is Chinese air space,” according to the Japanese Coast Guard.

The aircraft left without incident, but Fujimura called the move “extremely deplorable,” on a day when Chinese ships were also spotted in territorial waters.

“It is extremely regrettable that, on top of that, an intrusion into our airspace has been committed in this way,” he said.

Not to be outdone, China has now filed a protest as well:

China’s Foreign Ministry said on Thursday that Japan should halt entries into seas and airspace near disputed islets in the East China Sea, after Japan protested a flight over the islands by a Chinese plane.

The politics of the claims and counterclaims is somewhat confusing, particularly since it is a rare point of agreement between Beijing and Taiwan.  Both claim that the Senkaku Islands belong to China, but then again, both claim to be China.  They are much closer in proximity to Taiwan and China than mainland Japan, but Japan has claimed sovereignty for more than a century, annexing them in 1895. No one much cared about it until 1968, when oil was discovered nearby, and sovereignty became much more of an economic issue for the uninhabited islands.

It seems unlikely that the two rational governments in Beijing and Tokyo would allow this to come to a hot war between the two countries, especially given the small stakes involved.  Still, these kind of confrontations can end in very irrational ways, and further provocations from China might touch off something very ugly in the East China Sea.