Taiwan lies off the coast of southeast China and has been claimed by its Communist leadership for more than seven decades.

However, the democratically governed island has never been ruled from Beijing, thanks in part to American military backing, which has come in the form of numerous defensive arms sales over the last 40 years.

The trip—first reported by Reuters and later confirmed by the Taiwan Presidential Office—is being led by Mike Mullen, former chairman of the Joint Chiefs of Staff in the George W. Bush and Barack Obama administrations.

Mullen’s group will include Meghan O’Sullivan, a former deputy national security adviser under Bush; and Michele Flournoy, who was under secretary of defense under Obama—and once tipped to lead the Defense Department under Biden.

Also joining the group are Mike Green and Evan Medeiros, officials who served as China directors on Bush and Obama’s respective national security councils. Taiwan defense reporter Tingting Liu, with local broadcaster TVBS, said the bipartisan delegation would arrive by a chartered flight at Taipei’s Songshan Airport after 3 p.m. local time on Tuesday.

Following the start of Russian President Vladimir Putin’s military offensive against Ukraine last Thursday, the name “Taiwan” began trending on Twitter as Americans—including elected officials—predicted the possibility of Chinese leader Xi Jinping making his own moves on the island, which sits 80 miles across the Taiwan Strait.

In Taiwan, U.S.-skeptic opposition figures have used the opportunity to sow fear among the public and cast doubt on Washington’s commitments, members of Taiwan’s ruling party said over the weekend.

An unnamed U.S. official who spoke to Reuters didn’t link the upcoming visit to the ongoing attack on Ukraine or Taiwan’s decades-long anxieties about Beijing’s intentions.

“The selection of these five individuals sends an important signal about the bipartisan U.S. commitment to Taiwan and its democracy, and demonstrates that the Biden administration’s broader commitment to Taiwan remains rock solid,” the official was quoted as saying.

The delegation is scheduled to meet Taiwan’s President Tsai Ing-wen, her national security officials as well as Defense Minister Chiu Kuo-cheng, before departing on Wednesday, the same day former Secretary of State Mike Pompeo and his China adviser, Miles Yu, are due in Taipei for their own four-day visit.

Mullen’s group is the second U.S. delegation that has been sent personally by Biden. A bipartisan group of ex-U.S. officials led by former Connecticut Democrat Sen. Chris Dodd was in Taiwan last April. The latest trip is expected to annoy Beijing, which opposes all interactions between the U.S. and Taiwan.

The Biden administration’s decision to send a party of former American officials to Taiwan coincides with China’s marking of the 50th anniversary of the Shanghai Communique, which was signed in February 28, 1972, during former President Richard Nixon’s secret trip to the country.

The communique—the first of three between the U.S. and China—paved the way for formal diplomatic relations between Washington and Beijing in 1979, at the expense of Taipei.

U.S. policy over the past four decades has been to maintain robust unofficial ties with Taiwan. Under the Taiwan Relations Act of 1979, a law supported by Biden when he was a junior senator from Delaware, successive American administrations have been obliged to sell defensive weapons to the island in order to bolster its self-defense against China’s attempts to seize it by force.

However, the legislation doesn’t include a security guarantee; that is, a long-standing position of “strategic ambiguity” means the U.S. declines to say outright whether American forces would come to Taiwan’s defense in the event of a Chinese invasion, despite personal signals from Biden himself.

On Monday, Taiwan’s former President Ma Ying-jeou of the opposition Kuomintang party, who was in office between 2008 and 2016, remarked on the potential for a U.S. military response to another Taiwan Strait crisis by saying: “The Americans … will sell us weapons and provide us with intelligence, but they won’t send troops.”