Donald Trump is almost certain to attach great importance to the U.S.-Japan alliance if he returns to the White House, one of his former aides said Wednesday.

"I predict a lot of continuity, and the same things that motivated him when he was elected the first time, I think, continue to motivate him," Alexander Gray, who was deputy assistant to the former president, said in an interview with Kyodo News.

Alexander Gray. (Kyodo)

For Trump, Gray said that China would likely be regarded as the greatest threat to national security, and his foreign policy approach, with a strong emphasis on enhancing deterrence capabilities, is more relevant in 2025 than it was in 2017 when first he took office.

Referring to the decades-old U.S.-Japan alliance, he said it is "beyond any one prime minister, any one president. It has such extraordinary strategic significance" to serve U.S. interests and ensure stability in the Indo-Pacific region.

He also shrugged off deep-seated speculation should Trump win the November general election, he would significantly alter the trajectory of U.S. foreign policy set forth by the administration of President Joe Biden, which has been marked by a focus on multilateral cooperation.

"My sense is he doesn't have a preference. If you asked him that question, I don't think he'd have a preference. I think his preference is for alliances that work, whether it's U.S.-Japan, or U.S.-Japan-South Korea, or NATO or whatever it might be," he said. "If it's effective, if it keeps the peace and if it serves U.S. interests, I think the (former) president is all for it."

In his view, the Biden administration has inherited the elevation of the U.S.-Japan relationship from Trump's era and cooperation of the two countries is set to deepen across various domains, ranging from defense to economic security, and extend its reach to Southeast Asia, the Middle East and beyond.

Asked about what may be the biggest foreign policy issue for a second Trump presidency, Gray, who helped to shape the previous administration's approach to Asia, said, "China will continue to be probably the dominant focus."

Gray, who was also chief of staff of the National Security Council, said China is "more malign than before" on the trade front "so I absolutely think there's going to be a significant increase in tariffs, maybe as high as 60 percent."

He also spotlighted that China and Russia are more integrated as "an axis of autocracy" than when Trump was president.

He contended that the increasing alignment between Beijing and Moscow in an anti-American partnership is partially attributable to the shortcomings of the Biden administration.

"It's going to be very difficult to separate the two the way we were really able to in (former) President Trump's first term," said Gray, who is now chief executive officer of American Global Strategies LLC.

The failure came despite Trump's "greatest historical legacy" of transforming Washington's approach to Beijing "180 degrees from his predecessor" Barack Obama.

"When I started, there were still big parts of the U.S. government that viewed China as a potential friend and partner," he said. "When I left, every agency of the U.S. government was focused on how do we win a great power competition."

Similarly, he expressed disappointment over North Korea's deepening ties with Russia, whose utilization of Pyongyang's artillery shells to kill Ukrainians has destabilized the security situation not only on the Korean Peninsula but also elsewhere in the world.

"So, you know, as much as I think (former) President Trump wants to have reduction of tensions, the world has changed for the worse under President Biden, and that's just a reality he's going to have to confront," he said.

Related coverage:

Biden, Trump seal presidential nominations