STEVE INSKEEP, HOST:
NPR's Tom Bowman reports that a confrontation like this has been building for some time.
TOM BOWMAN, BYLINE: Just six months ago, the Pentagon released its annual report on China's military. The country's defense budget was growing. It was building more stealthy aircraft, submarines. It even bought an aircraft carrier from the Ukraine. At the time, Pentagon official David Helvey highlighted particular areas of concern.
DAVID HELVEY: In recent years, China has begun to demonstrate a more routine and capable presence in both the South and East China Seas.
BOWMAN: The East China Sea, that's exactly where regional anxieties have increased. China wants all aircraft to check in when they fly through its new air identification zone.
DAVID FINKELSTEIN: This has been slowly escalating over the past year.
BOWMAN: David Finkelstein is a China expert at the Center for Naval Analyses, a Pentagon think tank. He says both Chinese and Japanese planes and ships have been circling each other.
FINKELSTEIN: We started seeing a lot of activity with their respective coast guards, civilian paramilitary vessels and aircraft playing cat and mouse out there.
BOWMAN: The cat and mouse game is continuing. Both the U.S. and Japanese military aircraft are ignoring the new identification zone. The Pentagon in particular fears a repeat of an incident back in the spring of 2001. That's when a Chinese fighter jet slammed into a U.S. reconnaissance aircraft it was tailing in the skies above the South China Sea - inside what China called its Exclusive Economic Zone. China detained the American crew.
The situation now could lead to a far more dangerous situation, says Finkelstein and others. That's because it involves Japan and the long history of confrontation between the two countries.
CHENG LI: China and Japan cannot get along well for various reasons.
BOWMAN: Cheng Li is with the Brookings Institution. He says one of those reasons is Japan's brutal occupation of China during World War II that included the use of chemical and biological weapons. Japan has long been criticized for glossing over its recent past.
LI: So Japanese never acknowledged the terrible things that they conducted in World War II. And so there is a very strong anti-Japanese sentiment.
BOWMAN: Add to that China's other main complaint - its assertion of sovereignty over territory claimed by Japan and others.
FINKELSTEIN: Anything that has to do with sovereignty is a visceral, open wound in China's body. So number one, this is an issue about sovereignty.
BOWMAN: Again, David Finkelstein.
FINKELSTEIN: I think it's because it's about sovereignty with Japan and those wounds still have not healed.
BOWMAN: So the current dispute has a long past. Doug Paal served as an unofficial representative to Taiwan under President George W. Bush. Now he's with the Carnegie Endowment for International Peace. He says a key question is this: What will China do if Japanese aircraft violate the new zone?
DOUG PAAL: They have a long list of possible behaviors from attempting to shoot down the Japanese aircraft because it's violated space. Or intercepting the aircraft and telling them to leave. Or ignoring the aircraft as it flies over. We need to have conversations with the Chinese about what their intentions are.
BOWMAN: That's what the U.S. wants right away, to understand China's intentions. In the long term, by 2020, the Pentagon says, China has this goal: being able to fight and win two regional conflicts, including one in the East China Sea. Tom Bowman, NPR News, Washington.