New U.S. Defense Secretary Pete Hegseth pledged to work with Washington’s allies and partners Saturday in a message to the Defense Department as he took up his post at the Pentagon.

In the short message, Hegseth appeared to try and dispel concerns stewing in allied capitals such as Tokyo and Seoul that the U.S. under President Donald Trump could mean a return to a more transactional approach to foreign policy.

“We will work with allies and partners to deter aggression in the Indo-Pacific by Communist China, as well as supporting the President's priority to end wars responsibly and reorient to key threats,” Hegseth wrote in the letter. “We will stand by our allies — and our enemies are on notice.”

Hegseth, who also pledged to “revive the warrior ethos and restore trust” in the U.S. military, had faced a firestorm of criticism for his views on what he has said is a “woke” military that he believes has been weakened by its diversity.

Most well-known for his stint as a Fox News host, Hegseth is also a U.S. Army combat veteran. But critics had assailed him following his nomination to the post for a lack of experience in managing an organization as massive as the Defense Department, which counts some 2.1 million service members, 780,000 civilians and a budget of nearly $850 billion.

In his message, Hegseth also laid out a handful of other goals for the Pentagon, including strengthening the U.S. defense industrial base and making his department’s notoriously cumbersome processes for buying new weapons more efficient.

“We will rebuild our military by matching threats to capabilities,” he wrote. “This means reviving our defense industrial base, reforming our acquisition process, passing a financial audit, and rapidly fielding emerging technologies. We will remain the strongest and most lethal force in the world.”

Hegseth was confirmed by a knife-edge 51-50 vote — the thinnest margin for a defense secretary’s confirmation since the position’s 1947 creation — with Vice President JD Vance forced to cast a tiebreaking vote after three Senate Republicans joined all Democrats in voting against him.

Former Senate Majority leader Mitch McConnell, one of the three Republicans to vote against Hegseth, said that Trump’s nominee had failed to demonstrate that he will pass the numerous tests that would qualify him for a post that has “staggering consequences for the security of the American people and our global interests.”

"Mr. Hegseth provided no substantial observations on how to defend Taiwan or the Philippines against a Chinese attack, or even whether he believes the United States should do so,” McConnell said in a statement Friday. "He failed, for that matter, to articulate in any detail a strategic vision.”

McConnell also took Hegseth to task for an apparent lack of awareness of some of the more pressing challenges that he will confront out of the gates. These included China and North Korea’s growing ties with Russia and how to bolster U.S. alliances, as well as the best way to best tackle challenges facing the U.S. defense industrial base that have been highlighted by the war in Ukraine.

“Absent, too, was any substantive discussion of countering our adversaries’ alignment with deeper alliance relationships and more extensive defense industrial cooperation of our own,” McConnell said.

Japanese officials have privately expressed concerns about Trump’s return to the White House, and the possibility that he could ask Tokyo to pay more for hosting U.S. troops or boost its defense budget even further. Fears of a trade war, including of looming tariffs for Japanese automobiles, steel and other items, have also grown under Trump’s “America First” mantra.

Nevertheless, Japan has said it is aiming to take the alliance to “new heights” as the government looks to set up the first meeting between the mercurial U.S. president and Prime Minister Shigeru Ishiba, possibly as early as next month.