Just weeks after John Bolton's hard-line rhetoric infuriated North Korea and nearly derailed a planned summit between Kim Jong Un and President Donald Trump, the U.S. national security adviser appears to have taken a back seat to Secretary of State Mike Pompeo for the historic meeting.

While the hawkish Bolton — who has adopted a lower-key approach in recent days — is expected to be in Singapore for the talks on Tuesday, Pompeo has taken the lead as the administration assumes a softer tone toward Pyongyang ahead of the summit, several U.S. officials said.

Pompeo's rise combined with Bolton's more muted public role illustrates how the sometimes messy power dynamic in Trump's inner circle has played out going into the first-ever meeting between U.S. and North Korean leaders.