BRUSSELS -- US Defense Secretary Mark Esper announced on Thursday that the United States and the Taliban have negotiated a proposal for a seven-day reduction in violence in Afghanistan.

"We've said all along the best, if not only, solution in Afghanistan is a political agreement," Esper told reporters following a two-day NATO defense ministerial meeting in Brussels.

Without giving any clear timetable, Esper only said "progress has been on this front, and we have more to report on that soon."

He said consultations have been made with US allies about the proposal, and bilateral and collective meetings have been held to discuss the path forward.

Wrapping up the ministerial meeting, during which the situation in the war-torn country was high on the agenda, NATO Secretary General Jens Stoltenberg reaffirmed the alliance's support for the peace process.

"We welcome any steps that can lead to the reduction of violence -- the Taliban have to show a real will and a real ability to deliver a reduction of violence on the ground," said Stoltenberg.