Seoul and Washington decided to delay their wintertime joint air exercises to support diplomacy with Pyongyang, the two allies said on Sunday, which is seen by an analyst as a way to increase US' bargaining position in upcoming nuclear talks with the Democratic People's Republic of Korea.

US Secretary of Defense Mark Esper and the Republic of Korea's Defense Minister Jeong Kyeong-doo announced the decision at a joint news conference on Sunday.

The joint drills were scheduled to begin in the next few days.

"We made this decision as an act of goodwill to contribute to an environment conducive to diplomacy and the advancement of peace," Esper said.

"We encourage Pyongyang to demonstrate the same goodwill as the considerate decision on conduct of training, exercise and testing," he said, urging Pyongyang to "return to the negotiating table without precondition or hesitation".

The drills, known as the Combined Flying Training Event, would have simulated air combat scenarios and involved an undisclosed number of warplanes from both the United States and the ROK, Reuters reported.

Earlier this month, a senior diplomat from the DPRK blamed the joint air drill for "throwing cold water" over talks with Washington.

It was unclear whether the decision by Washington and Seoul would kick-start talks with Pyongyang, but according to Li Chengri, a researcher at the Chinese Academy of Social Sciences, the decision came as the US hopes to increase its negotiating leverage in preparations of possible talks with the DPRK before the end of the year.

On Thursday, the DPRK said the US had proposed a resumption in December of stalled talks but did not say whether it would accept the offer.

"The delay of the exercises is to create a friendly atmosphere to invite the DPRK back to the negotiation table. But it won't fundamentally solve the nuclear issue as the ROK and the US could also resume exercises at any time," Li said.

Asked when the US and ROK would hold the postponed drills, the ROK's Jeong declined to offer any sense of timing.