Reluctant to cede any ground, Tokyo has been urging Japanese commercial flights not to notify China before flying through the zone.
Word that the U.S. had advised American commercial carriers to comply rankled leaders in Tokyo, who are hoping a united front with the U.S. will increase pressure on Beijing to reverse course.
But senior Obama administration officials said Tuesday that the U.S. never told American commercial carriers to comply specifically with China's demands.
Rather, the Federal Aviation Administration merely reaffirmed existing policy that pilots should comply with such instructions anywhere in the world, said the officials, who weren't authorized to comment by name and demanded anonymity.
The zone covers more than 600 miles from north to south, above international waters separating China, South Korea, Japan and Taiwan. China says all aircraft entering the zone must notify Chinese authorities beforehand or face unspecified defensive measures.
Although the U.S. has joined Japan and other allies in refusing to recognize the zone, Washington has treaded carefully, wary of creating a new fault line in its relationship with China just as the U.S. is pursuing a new era of economic cooperation with Beijing.
The show of unity between Biden and Abe will be closely watched by China, as well as other Asian nations worried that the new defense zone may portend further steps by China to assert control in the region.
On Monday, China's ambassador to the Philippines claimed China has a sovereign right to establish a similar zone over the South China Sea, where China and the Philippines are locked in another long-running territorial dispute.
The feud promises to trail Biden throughout his weeklong trip to Asia—a tour intended to affirm Washington's continued interest in upping its presence in the region, in part to counter China's growing influence.
After a working dinner with Abe on Tuesday night, Biden will fly to Beijing on Wednesday to meet with Chinese President Xi Jinping, where officials said Biden would raise U.S. concerns over the zone directly.
Biden will then travel Thursday to South Korea—another U.S. ally at odds with China over the air defense zone.
Japan, which claims the islands as its own, is concerned that compliance with China's demands will allow China to slowly solidify its claim to the tiny islands and the strategically important waters that surround them.
The United States sees rising tensions between China and its neighbors as a threat to U.S. interests, and is concerned that the tense atmosphere increases the likelihood of an incident in the air spiraling out of control.
The U.S. doesn't take a position on the islands' sovereignty but acknowledges that Japan administers them, meaning U.S. treaty obligations to defend Japan could come into play.
After a morning meeting with Japanese lawmakers and Deputy Prime Minister Taro Aso, Biden made his way to Shibuya, a bustling Tokyo district and fashion center, where he toured a technology company founded by a female entrepreneur to highlight the role of women in Japan's economy.
U.S. Ambassador to Japan Caroline Kennedy joined Biden as he mingled with young employees in a chic, 24th floor lunchroom overlooking Tokyo's sprawling skyline.
At a roundtable later with business executives, Biden said he'd heard some say women are good in the workforce because they are kinder and gentler.
“I've never found that to be the case,” Biden said to laughter. “They're as tough, they're as strong, they're as everything as a man is—and vice-versa.”
