Prime Minister Shinzo Abe received the assurance of visiting U.S. Vice President Joe Biden Tuesday that Washington stands behind Japan as it responds to China’s recent declaration of an air defense identification zone in the East China Sea that encompasses the Japan-administered Senkaku Islands.

During their 85 minutes meeting in Tokyo, Abe and Biden agreed that they won’t accept China’s recent establishment of the ADIZ and Japan and the U.S. will cooperate closely to deal with the issue.

“The U.S. is deeply concerned by the attempt to unilaterally change the status quo in the East China Sea. This action has raised regional tension and increased the risk of accident and miscalculation,” Biden said at a joint news conference held following their talks.

“The world should not forget that our alliances have been critical to the stability that has made this region’s remarkable progress possible. And I told the prime minister that we will remain steadfast in our alliance commitment,” Biden said, adding that he will discuss the issue directly with the Chinese leadership when he goes to Beijing on Wednesday.

Abe said operations by the Self-Defense Forces and the U.S. military won’t change because of China’s ADIZ.

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“We further agreed that we will not condone any action that could threaten the safety of civilian aircraft,” he said.

Abe and Biden also vowed to cooperate on paving the way to conclude the Trans-Pacific Partnership agreement by the end of the year, as planned by President Barack Obama. Chief negotiators from the 12 member countries are scheduled to hold talks from Saturday in Singapore.

“We need a comprehensive agreement that resolves long-standing differences between the U.S. and Japan, including issues like agriculture and automobiles. And it’s difficult,” Biden said.

“But the TPP will increase trade and investment, help our businesses, create jobs and put in place a powerful constituency for open markets for rules-based competition,” he said.

Regarding U.S. bases in Okinawa, Abe and Biden also agreed to try to reduce the prefecture’s burden of hosting the bulk of U.S. forces in Japan by advancing the long-stalled plan to build an airstrip in Henoko in northern Okinawa Island to replace U.S. Marine Corps Air Station Futenma in the crowded city of Ginowan.

Okinawa Gov. Hirokazu Nakaima must decide whether to approve Tokyo’s request to begin the necessary work at Henoko to build the replacement facility.

Biden’s visit comes less than two weeks after China’s declaration of its ADIZ, which overlaps with those of Japan and South Korea, sparking strong criticism from Tokyo and Washington.

The move is widely seen as Beijing asserting its claim to the Senkakus, claimed also by Taiwan.

Following its establishment on Nov. 23, Beijing said all aircraft flying in the zone must obey its rules, including submitting flight plans, or face “defensive emergency measures” by the its military.

While both Tokyo and Washington have rejected China’s ADIZ claim, their advice to commercial carriers differs. Washington has effectively encouraged airlines to comply while Tokyo is urging carriers to ignore China’s demand.

At the residence of new U.S. Ambassador Caroline Kennedy earlier Tuesday, Biden met with Deputy Prime Minister Taro Aso and other lawmakers, including Liberal Democratic Party Secretary-General Shigeru Ishiba and Democratic Party of Japan leader Banri Kaieda.

During the talks, Biden criticized China’s establishment of the ADIZ, Kaieda told reporters after the meeting.

Kennedy and Daniel Russel, assistant secretary of state for East Asian and Pacific affairs, also attended the meeting.

The vice president also met with Crown Prince Naruhito and his wife, Crown Princess Masako, at their residence at the Akasaka Estate before his talks with Abe.

Biden arrived in Tokyo Monday night, on the first leg of a weeklong trip to Tokyo, Beijing and Seoul. He plans to meet with Chinese President Xi Jinping Wednesday before meeting South Korean President Park Geun-hye in Seoul on Friday.

Information from Kyodo added