TOKYO -- U.S. Deputy Secretary of State Wendy Sherman on Wednesday said Washington maintains its longstanding stance on Taiwan but has deepened ties with the island, while looking to shore up deterrence.

"First of all, we are continuing our One China policy," Sherman told Nikkei Asia and other Japanese media outlets in a roundtable discussion in Tokyo. "That said, we have deepened our relationship with Taiwan."

Sherman is in Japan as part of a weeklong tour focused on Indo-Pacific security, with stops in South Korea and Mongolia. She said the U.S. has established a "stronger economic relationship [as well as] a stronger political and security relationship with Taiwan."

China has shown increasing assertiveness regarding its claim to Taiwan, including air incursions and the fiery rhetoric of President Xi Jinping's July 1 speech celebrating the Communist Party's 100th anniversary. Xi vowed to crush any attempt to declare independence in Taiwan.

Under the "One China" policy the U.S. has maintained since 1979, Washington "acknowledges" Beijing's position that there is only one China and that Taiwan is part of it, but does not explicitly recognize Chinese sovereignty over the island.

The U.S. continues to tread carefully. Sherman's comments echoed those of President Joe Biden's Indo-Pacific coordinator, Kurt Campbell, who said earlier this month that the administration does not support Taiwan independence and understands the sensitivities but wants "a strong unofficial relationship" with Taipei.

Yet as Beijing escalates its rhetoric and military moves, Washington and its partners are showing a united front and preparing for contingencies. In an usually unequivocal statement, Japanese Deputy Prime Minister Taro Aso argued on July 5 that in the event of an attack on Taiwan, "Japan and the U.S. must defend Taiwan together."

Sherman told the roundtable, "We share concerns with Japan about increasing aggressive action and concern, as we said, given other actions taking place such as in Hong Kong."

"And so we are talking with Japan and other allies and partners about the best approach to ensure deterrence. Everyone wants to ensure peace, security and stability in the Taiwan Strait, and so we will work together to try to do so."

The U.S. is in the midst of large-scale military drills in the Pacific region. It kicked off the biennial Exercise Talisman Sabre with Australia last week, with a number of allies including Japan, South Korea and the U.K. taking part and others such as India and Germany observing.

Earlier this year, the Group of Seven leading democracies mentioned Taiwan in a communique for the first time, underscoring "the importance of peace and stability across the Taiwan Strait" and encouraging "the peaceful resolution of cross-Strait issues."

As for China itself, Sherman said the U.S. remains "ready to engage" with Beijing. "It's a multi-faceted relationship. I think it will stay a multi-faceted relationship for some time to come."

On when Biden would meet with Xi, she explained that the U.S. would "take on other engagements" when it "makes sense to do so," vowing to "constructively and responsibly manage this complex relationship."

Sherman on Wednesday also held a trilateral meeting with Japanese Vice Foreign Minister Takeo Mori and South Korean First Vice Foreign Minister Choi Jong-kun. The trio discussed their commitment to a "rules-based international order" and opposition to "coercive behavior" in the Indo-Pacific, among other issues including North Korean denuclearization.

Her trip comes as Washington actively strives to shore up ties in the region. U.S. Defense Secretary Lloyd Austin is scheduled to visit Singapore, Vietnam and the Philippines from later this week.