"First, Trump and Moon do not have a close personal relationship," she wrote in comments to reporters. "I think that Moon's dual-track approach to North Korea -- pursuing engagement with Pyongyang, even as his administration steps up the pressure, including the most recent unilateral sanctions -- is likely to cause some friction in the summit meeting."

Pak, currently the Korea chair at the Brookings Institution, said Trump is still expected to reinforce the US commitment to the bilateral alliance and praise South Korea's rise.

"Trump's trip to South Korea is an excellent opportunity to showcase the strength of the alliance relationship," she noted. "I am concerned about the potential for divergence, however, given Washington's repeated comments alluding to military strike options against North Korea and South Korea's desire to maintain peace and find ways to engage with the North."

Trade is also likely to figure prominently in the summit.

"While I am hopeful that Trump will appreciate the visit to (US military base) Camp Humphreys -- a key symbol of South Korea bearing the costs of the alliance -- it is unlikely to mollify Trump's stance on (the South Korea-US free trade agreement) and his insistence on addressing trade imbalances," Pak said. (Yonhap)