Vice-President Joe Biden’s strong reaffirmation of the U.S.-Japan alliance is better news following bad. The bad news is what made the American reaffirmation necessary: China’s latest act of “barbed wire diplomacy,” the extension of its Air Defense Identification Zone to include a disputed chain of Japanese-administered islets northwest of Okinawa.

The Japanese call the disputed islets the Senkakus. The Chinese call them the Diaoyu.

Two names for a territory may simply be colloquial artifacts. When the history is ugly, however, one man’s idiom is another man’s curse. “Double names” are often the cartographer’s mark of lingering animosity between neighboring states. Many Chinese, with good reason, resent Imperial Japan’s brutality during World War 2. When Beijing spars with Tokyo, Chinese nationalists applaud — at least that is one interpretation.

This ADIZ’s line of barbs, however, also snagged another major American ally in East Asia. The zone includes a reef claimed by South Korea. Ay, there’s the rub.

Official U.S. policy is to bridge the animosity. The U.S. recognizes current Japanese authority, but wants China and Japan to solve the dispute peacefully. However, an ADIZ involves air defense, which involves a military threat. Aircraft entering a recognized ADIZ must identify themselves to the national air controllers. If they fail to do so, they may go down in flames.

Implicit armed threat is another rub — for Washington. Last week, after China declared the new ADIZ, the Obama Administration tested it, vigorously. Two unarmed B-52s flew through the zone. The bombers did not identify themselves to Chinese air controllers; Chinese interceptors didn’t disturb them.

Bluff called and miscalculation revealed?

After the B-52 sorties, Washington told U.S. civilian aircraft to recognize the ADIZ. If the flinch is defensible as caution and a diplomatic gesture to China, Japan ordered its civilian aircraft to ignore the ADIZ completely.

Hasty miscalculation by Chinese nationalists remains the Obama Administration’s preferred explanation for the ADIZ.

In Tokyo this week (on his way to visit Chinese president Xi Jinping), Vice-President Biden told Japan’s Prime Minister Shinzo Abe that the U.S. firmly supports Japan’s rejection of China’s claim. “The U.S. and Japanese security liaison,” Biden said, “is the cornerstone, not merely in the Pacific region, but the cornerstone on which our security is built for the next 20 years.” Biden’s statement reaffirmed an economic and geo-strategic fact. The U.S. sees Japan as an essential global security partner, not a Pacific Ocean trip wire.

Abe called Biden’s visit “timely,” which it was. He described “the security environment in the Asia-Pacific region” as “increasingly severe.” And it is.

Biden and Xi have meetings with photo ops. Good diplomatic guests, on what was touted as a friendly meet and greet, don’t scold their hosts, at least not too overtly. With that in mind, Biden avoided directly branding China’s expanded ADIZ gambit as a grave diplomatic error. Still, at a subsequent news conference, the vice-president lamented the “risks of miscalculation” in Asia. His palpable innuendo provides Beijing with a diplomatic line of retreat.

But did Beijing really miscalculate?

For decades, China has been expanding its perimeter, with re-asserting historical Chinese rights to territory as the reason, or excuse. China used it in 1950 when it invaded Tibet. In 1962, China drove India from disputed Himalayan territory. In the 1970s, China renewed claims to islands held by Vietnam and seized them. Then China began producing maps of the South China Sea extending its maritime borders — lots of provocative dotted lines. Now Chinese and Filipino ships clash over disputed seas.

China, ultimately diplomatic, backs its dotted line claims with military muscle — and barbed wire.

With Japan and South Korea, China faces tougher opponents, so the extended barbed wire hides behind the label “defense.” Yes, miscalculation may be Beijing’s tactical excuse. But including South Korea was definitely part of the message. Beijing is telling Washington that future relations hinge on the U.S. accepting extended Chinese hegemony in Asian waters. If that brings a grimace to Joe Biden’s photo op face, so be it.

Austin Bay is a syndicated columnist.