Oil prices retreated on Monday after the U.S. pulled back from initial sanctions threats against Colombia, reducing immediate concern over oil supply disruptions, though U.S. President Donald Trump's muscle-flexing is keeping markets twitchy.

WASHINGTON (Reuters) — President Donald Trump said on Sunday he will impose sweeping retaliatory measures on Colombia, including tariffs and sanctions, after the South American country turned away two U.S. military aircraft with migrants being deported as part of the new U.S. administration’s immigration crackdown.

Oil market momentum was kept in check on Monday as prices fluctuated in and out of negative territory, with traders on edge despite the U.S. pulling back from initial sanctions threats against Colombia,