"We think that a political solution is the best way forward to denuclearize the Peninsula and to address North Korea's programs," Esper told reporters on Friday at Pentagon during a joint press conference with Chairman of the US Joint Chiefs of Staff Mark Milley, Xinhua reported.
The Pentagon chief expected that the US and North Korea could still pursue the diplomatic path over the nuclear issue.
"I remain hopeful that we could get the process started again," he said.
In the meantime, both Esper and Milley stressed that US military forces are in a high state of readiness and "prepared to fight and win tonight if need be."
Pyongyang set its deadline for denuclearization negotiations at the end of this year, which was rejected by US special representative for North Korea, Steven Biegun.
Biegun, who just has been confirmed as deputy secretary of state, said earlier this week in his meeting with South Korean President Moon Jae-in that the US was unwavering in its efforts to denuclearize the Korean Peninsula via dialogue and diplomacy.
North Korea's Vice Foreign Minister Ri Thae Song warned early December that Washington would soon need to decide what kind of "Christmas gift" it will receive from Pyongyang.
North Korea said it had carried out two "important tests" early this month. "I'd be disappointed if something would be in the works, and if it is we will take care of it," US President Donald Trump told reporters on Monday when asked about the latest developments in North Korea.
( With inputs from IANS )