U.S. Defense Secretary James Mattis will seek to reassure allies worldwide that they can still rely on an increasingly inward-focused America as he heads to East Asia on the first overseas trip by a Trump administration Cabinet member.

The retired U.S. Marine Corps general leaves Wednesday for South Korea and Japan — two of Washington’s closest allies — amid questions about President Donald Trump’s commitment to the region, having pulled out of a 12-nation Pacific trade deal and suggesting previously that Asian nations weren’t paying enough for U.S. troops stationed in their countries.

“It’s a reassurance message,” said one Trump administration official, speaking on condition of anonymity.

“This is for all of the people who were concerned during the campaign that then-candidate, now-president, Trump was skeptical of our alliances and was somehow going to retreat from our traditional leadership role in the region.”

Questions over ties with Tokyo and Seoul come against the backdrop of an increasingly belligerent regime in North Korea under Kim Jong Un. Pyongyang appears to be making preparations for another nuclear or missile test and has been advancing its weapons capability, with Trump saying he would not allow North Korea to threaten U.S. soil.

“It’s still very important to reassure allies at the time when there’s so much uncertainty, turbulence, unpredictability,” said Patrick Cronin, senior director of the Asia-Pacific Security Program at the Center for a New American Security in Washington. The trip “will reverberate beyond those two key Northeast Asian allies when you have a revered secretary of defense put boots or wingtips on the ground and reassure the leaders.”

The Pentagon downplayed expectations of any immediate shift in the U.S. military’s approach toward the region or in its presence. South Korea hosts about 28,500 U.S. troops, while Japan has 50,000.

Mattis “wants to find out what their concerns are, learn more about the issues that we face together and prepare to address those,” Pentagon spokesman Jeff Davis said. “He’s primarily in listening mode right now.” Davis added that “the intent of this is not to roll out any big change in U.S. policy.”

Nevertheless, Mattis’ trip will be “high-level signaling” to key allies, Cronin said.

South Korea, the first stop, is facing turbulence after President Park Geun-hye was impeached over an influence-peddling scandal. Acting President Hwang Kyo-ahn spoke to Trump by phone Sunday, with the U.S. president reiterating the America’s “ironclad commitment to defend” it against North Korea. Trump said the alliance will be “better than ever before,” according to a statement on the call from Hwang’s office.

In addition to discussing joint defense capabilities, Mattis will meet with South Korean Foreign Minister Yun Byung-se to discuss North Korea.

By sending Mattis to South Korea first, Trump is delivering a message the U.S. will preserve its alliance and sending a warning to Pyongyang, said Baek Seung-joo, a former deputy defense minister who is a lawmaker with the ruling Saenuri Party. His trip also sends indirect signals to China that the U.S. stands by a plan approved during the Obama administration to deploy in South Korea the Terminal High Altitude Area Defense (THAAD) missile defense system, which Beijing opposes, Baek said.

“His visit will clarify and kill some blurry areas and extreme talks that have been hovering around before the start of the Trump administration,” Baek said. “While Obama excluded chances of any military actions against the North, I think Trump will leave such chances, including a surgical strike, ambiguous.”

U.S. allies and adversaries will also be watching for more direct signals toward Beijing. Trump has stoked fears of a trade war by threatening to label China a currency manipulator and weighing tariffs on Chinese goods. Meanwhile, Trump’s choice for secretary of state, Rex Tillerson, suggested during a confirmation hearing that the U.S. would toughen its stance over China’s island-building efforts in the disputed South China Sea.

Tensions with Beijing escalated last week when Trump’s White House vowed to defend “international territories” there.

China responded by saying it had “irrefutable” sovereignty over disputed islands in the strategic waterway.

“What U.S. military people say is that considering the pace of China’s military build-up such as anti-ship missiles and fighters, there are worries about Japan’s capabilities,” said a senior Japanese Defense Ministry official, speaking on condition of anonymity.

Mattis’ visit to Japan comes ahead of a Feb. 10 meeting in Washington, where Prime Minister Shinzo Abe will sit down with Trump for the second time since his election. The U.S.-Japan alliance, a bedrock of security in the Pacific region, has come under stress since Trump backed out of the Trans-Pacific Partnership trade accord shortly after taking office. Abe, a key advocate of the deal, has indicated he is open to bilateral trade talks between the U.S. and Japan.

“I want to hold frank discussions with Secretary Mattis about various issues and to make it a meeting that contributes to deepening and strengthening the alliance and making it unshakable,” Defense Minister Tomomi Inada told the Diet this week.

Japan will also be seeking assurances Trump will hold to the Obama administration’s pledge to come to its defense if needed over the Senkaku Islands in the East China Sea that are in dispute with China. China regularly sends planes and ships near the area, leading Japan to scramble fighter jets.

Some people in Japan are worried about whether Trump will act on his campaign rhetoric about U.S. troops in the region, according to Itsunori Onodera, a former defense chief.

“There is concern among a section of the Japanese people because he has said that protecting allies, including Japan, costs a great deal of money,” Onodera said. “We need to get things ready so that we are not in a panic if America’s thinking suddenly changes.”