US President Donald Trump is once again showing interest in direct diplomacy with North Korean leader Kim Jong Un, even as his administration puts increasing pressure on South Korea, a long-standing US ally.

Trump has signalled that he wants to rebuild the relationship he developed with Kim during his first term and has pushed for another meeting. Reports indicate that he is seeking a possible meeting with the North Korean leader later this year.

A key recent move was Trump's decision to scale back US-South Korean military exercises. He argued that the drills were costly and could send the wrong message to North Korea, while also pointing to his positive relationship with Kim. The decision has raised concerns in Seoul about the reliability of the US security commitment.

At the same time, Trump's relationship with South Korea has become more transactional. Differences have emerged over defence spending, US troop costs, trade and Seoul's position on US military operations, including its decision not to participate in the US-led war against Iran.

Analysts say Trump's outreach to Kim is partly aimed at reviving his earlier diplomatic strategy. During his first term, Trump held three meetings with Kim, but those talks failed to produce a lasting agreement on North Korea's nuclear programme. North Korea's nuclear and missile capabilities have since become stronger, while its relationships with Russia and China have also deepened, making a new diplomatic breakthrough more difficult.

For South Korea, the shift is particularly sensitive. Seoul remains dependent on its alliance with Washington for deterrence against North Korea, but Trump's latest decisions have encouraged President Lee Jae Myung to emphasise stronger independent defence capabilities.

North Korea, meanwhile, has rejected Trump's latest diplomatic overtures and criticised the US-South Korean military exercises. Pyongyang has also continued demonstrating its military capabilities, including recent ballistic missile launches.

The contrasting approach reflects Trump's transactional foreign-policy style: pursuing direct engagement with an adversary he believes he can negotiate with, while demanding greater commitments from a traditional ally. Whether this strategy can restart US-North Korea diplomacy without weakening Washington's alliance with Seoul remains uncertain.