The U.S. official in charge of talks with North Korea says time is running short to achieve a deal, but not because of the end-of-year deadline set by Kim Jong Un (gihm jung oon).

U.S. envoy Stephen Biegun tells the Senate Foreign Relations Committee that any crisis or other distraction could derail talks.

Biegun says the “window is still open” but the North Koreans “need to seize the moment.” The envoy says Kim needs to grant more authority to his negotiating team.

Biegun says the U.S. has seen no “concrete evidence” that North Korea intends to denuclearize.

Negotiations faltered after the U.S. rejected North Korean demands for broad sanctions relief in exchange for a partial surrender of the North’s nuclear capabilities.