Administration officials said it was important to push back against China's dubious assertion of jurisdiction over international airspace. The Chinese policy requires foreign planes flying through the zone to identify themselves and file a flight plan, even if they are not flying into Chinese airspace.
The symbolism of B-52s' flying, with no advance warning, through China's zone spares Mr. Biden from having to play the tough guy. But experts said he needed to leave no doubt in talks with President Xi that the United States thinks the Chinese move was ill advised.
"It will have the Chinese scrambling aircraft time after time, especially if the Japanese play games with it," said Kenneth G. Lieberthal, a China adviser during the Clinton administration.
The vice president has firsthand experience of this. On a visit to Beijing in 2011, he presented Chinese officials with photographs taken by American pilots that documented how Chinese fighters, dispatched to intercept American planes flying surveillance missions off China's coast, sometimes came within 10 feet of their wingtips.
(Read more: US, Japan slam China airspace rules on islands)
Mr. Biden has cultivated an unusually personal relationship with Mr. Xi. The two traveled together in China and the United States, when Mr. Xi was vice president. That may make Mr. Biden more alert to the domestic political pressures the Chinese leader faces, as he embarks on risky economic reforms after a recent Communist Party congress.
"Chinese social media, official and semiofficial media are all playing up this dispute," said Cheng Li, a senior fellow at the Brookings Institution. "The U.S. has failed to understand how much weight the sovereignty issue carries with Asian countries."
The tensions are likely to increase. The Chinese Navy has put its only aircraft carrier out to sea, on a course toward the South China Sea. In the East China Sea, an American carrier group is joining Japanese warships for long-planned naval exercises.
With so much firepower in such hotly contested waters, experts said there was a real danger of miscalculation by either side. Mr. Biden, who will begin his trip in Tokyo, is expected to urge Mr. Abe to show restraint as well.
(Read more: China's reforms: 5 key ones you should know)
The good news for all concerned, China experts said, is that Mr. Xi is much less interested in military adventurism than in overhauling China's economy. "The chances of a real war are still low," Mr. Li said. "But sometimes incidents will push leaders into a corner."