U.S. Defense Secretary Mark Esper said Friday he believes the United States will be "tested soon" on bringing North Korea back to the negotiating table to discuss its nuclear weapons program.

Esper, speaking at the Council on Foreign Relations in New York, said the U.S. is trying hard to resume the negotiations because the threat of North Korea's nuclear and missile programs can only be resolved through a diplomatic agreement.

"War on the peninsula would be horrible. Nobody wants to see that," he said at the council, in live online footage. "I think we're going to be tested here soon -- test in the sense of this next stage, trying to get them back to the negotiating table, and hopefully not back on the other path."

Esper made the comments as he recalled the high tensions between Washington and Pyongyang when he took office as secretary of the Army in the fall of 2017, saying, "We were on the path toward conflict, because we were preparing for it."

Tensions between the sides have renewed in recent weeks as North Korea has ramped up pressure on the U.S. to come up with a solution to their stalled negotiations before the end of the year.

The North has strongly suggested it will resume nuclear or long-range missile tests if the U.S. fails to meet that deadline.