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,

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.

Colombian President Gustavo Petro announced that Colombia was suspending permission for previously authorized U.S. deportation flights to land in Colombia. Ostensibly driving Petro’s action were concerns that Colombian nationals were not being treated with respect during the deportation process because they were being transported by military aircraft.