Under Secretary of Defense for Policy Elbridge Colby is being sworn in by Vice President J.D. Vance in Washington on Apr. 9. (Colby's X account)
Under Secretary of Defense for Policy Elbridge Colby is being sworn in by Vice President J.D. Vance in Washington on Apr. 9. (Colby's X account)

A senior Pentagon official described President Donald Trump's defense policy Tuesday as "not a recipe for isolation" but a "common sense" approach amid lingering concerns about the potential impact of Trump's America First policy on US alliances and partnerships.

New Under Secretary of Defense for Policy Elbridge Colby made the remarks in a social media post on the day after he was sworn in by Vice President J.D. Vance last Wednesday to carry out a key role to flesh out America's defense strategy.

"This isn't a recipe for isolation. Instead, it's the common-sense approach. If we had continued on the old path, disaster would have been the result," Colby wrote on X, referring to Trump's defense policy.

"That is why President Trump's approach is so vital. His is a strategy that puts Americans' interests first and will restore peace through strength -- not just for a few years, but for decades to come," he added.

Trump has been hammering away at his America First policy, which many anticipated might be geared toward curtailing the United States' overseas military involvement and putting pressure on allies and partners to undertake greater security responsibilities -- a reason why some called it a strain of isolationism.

Last Tuesday, the Senate confirmed Colby for the Pentagon's No. 3 position.

Colby has advocated for an adjustment of US Forces Korea's role to focus more on threats from China.

During an interview with Yonhap News Agency last year, he noted the need for a USFK overhaul to make it "more relevant" to handling China-related contingencies rather than being held "hostage" to countering North Korean challenges.

Colby served as deputy assistant secretary of defense for strategy and force development from 2017-2018 during the first Trump administration. (Yonhap)