Victoria Nuland, the acting deputy secretary of State, said in a call with reporters late Monday night that she held “extremely frank” and “difficult” talks with the nation’s self-proclaimed chief of defense, Gen. Moussa Salaou Barmou, and three colonels supporting him.

The U.S., France and regional leaders in Africa are pushing for Niger’s coup leaders to abandon their overthrow of the democratic government or risk a military confrontation threatened by neighbors in the Economic Community of West African States (ECOWAS) and led by Nigeria.

Niger’s junta refused to step down by a Sunday deadline set by ECOWAS, and the heads of state of member nations are set to meet on Thursday to discuss next steps. They have said military intervention is a “last resort.”

The U.S. has carefully called the military takeover in Niger, which was launched on July 26, an “attempted coup” to maintain diplomatic channels that would otherwise be shut by a formal declaration.

Nuland’s visit to the capital of Niamey made her the highest-ranking U.S. official to meet face-to-face with Niger’s military junta, whose leaders have a long and personal history working with the American military.

Nuland was blunt about how Barmou and his backers were uncompromising in the face of U.S. offers for mediation, and that the military officials rejected Biden administration calls to meet with Niger’s detained president, Mohamed Bazoum, who is under house arrest with his family.