Republican Senator Thom Tillis says the decision allows North Korea to provide more support to Russia in Ukraine.

President Donald Trump is facing pushback over his decision to reduce joint military exercises between the United States and South Korea, with several Democrats accusing him of abandoning Washington’s allies.

Jack Reed, the top Democrat on the Senate Armed Services Committee, called the decision “inane”, saying that it sends a message that “America’s commitments are negotiable”.

“China and Russia are watching how easily this president abandons America’s allies and they will remember it the next time they test us,” Reed said in a statement on Monday.

Trump announced on Sunday that he had ordered the Pentagon to “substantially reduce” joint drills with South Korean forces.

He suggested that the decision is based on his “very good relationship” with North Korean leader Kim Jong Un, as well as Seoul’s refusal to join the US-Israel war against Iran.

“I recently asked the President of South Korea if they would like to join us in the denuclearisation of the Islamic Republic of Iran, and they said, ‘No thanks!’” Trump wrote on his Truth Social platform.

The US president often frames the war with Iran as a denuclearisation push, but Tehran says it does not possess a nuclear weapon.

The war games with South Korea are part of a decades-long defence partnership between the two countries, which includes the 1953 Mutual Defence Treaty that effectively placed Seoul under Washington’s security umbrella.

In a factsheet, the US State Department describes the strategic partnership with South Korea as a “linchpin for security and stability in the Indo-Pacific”.

Democratic Senator Andy Kim accused Trump of disregarding that partnership.

“Decisions about joint exercises need to be made jointly – and not announced unilaterally by social media,” Kim wrote on X.

“I will continue to press this administration to strengthen our security, economic, trade and technology ties – which all benefit the American people and the broader Indo-Pacific region.”

Congresswoman Pramila Jayapal called Trump’s decision “dangerous” for the region’s stability.

“So – our US wannabe authoritarian ruler has decided to ditch democracy in South Korea for the authoritarian rules in North Korea that he so admires?” Jayapal wrote in a social media post.

The new policy comes as the US moves away from a focus on the Asia-Pacific region – a doctrine informally dubbed “the pivot to Asia” – during strategic competition with China.

Trump’s National Security Strategy last year called for shifting US foreign policy resources to the Western Hemisphere, and the war with Iran has put further strain on Washington’s military and diplomatic bandwidth.

During his first term, Trump met three times with North Korea’s Kim between 2018 and 2019, following escalating tensions between Washington and Pyongyang.

After the summits, the US president hailed the rapport with Kim, but the talks did not lead to a diplomatic breakthrough or push forward the US policy objective of denuclearising North Korea.

Pyongyang has also continued its missile testing in defiance of the US and allies, including a launch earlier this month.

Reducing military exercises with South Korea has provoked a rare Republican criticism of Trump’s policies.

Republican Senator Thom Tillis argued that the decision allows North Korea to step up its support for Russian President Vladimir Putin amid the war with Ukraine.

“South Korea has been a solid military ally for over 70 years that possesses exquisite military capabilities,” Tillis wrote on X.

“Reducing joint exercises with South Korea does nothing more than free up thousands of North Korea’s troops to support Putin’s systematic kidnapping, torture, rape and murder of innocent Ukrainian citizens.”