Following months of strategic reticence, South Korea and the United States will soon reveal the schedule of their combined military drills, defense sources here said Monday.

"The two sides plan to announce the schedule of the joint training, postponed due to the PyeongChang Winter Olympics, on Tuesday," a source said.

The timetable and size of the annual Foal Eagle and Key Resolve exercise are a matter of primary concern with a flurry of summit diplomacy on North Korea's nuclear program just around the corner.

Military officials in Seoul said the upcoming drills will take place "on the level of previous years," which suggests no big change in the overall scale.

As usual, the Combined Forces Command will notify Pyongyang in advance of the training schedule and its position that the maneuver is defensive in nature. The message will be delivered via the United Nations Command Military Armistice Commission.

But many view the allies as seeking to play low-key this time when it comes to the major joint military maneuvers long condemned by Pyongyang as a token of hostility to its communist regime and rehearsal for invasion.

They plan to kick off the Foal Eagle field exercise in Korea on April 1 for a month-long run, another source said.

In connection with Foal Eagle, the two countries' Marines are slated to conduct the Ssangyong (double dragon) exercise, in which the USS Wasp, the US Navy's 40,500-ton multipurpose amphibious assault ship, is likely to take part.

Last year, Foal Eagle was staged from March 1-April 30, with some US strategic assets, including the USS Carl Vinson aircraft carrier, mobilized. Media were invited aboard the ship to cover its operation in waters near Korea.

Keen attention is being paid to whether the US will send such high-profile assets as aircraft carrier, nuclear submarine and strategic bomber this year, along with the number of its service members to join the practice.

The allies are expected to hold the Key Resolve command-post, simulation-oriented training for two weeks from April 23. It took place from March 13-24 in 2017.

They used to begin the joint training in late February or early March.

Late last year, the liberal Moon Jae-in administration of South Korea proposed putting it off until after the Olympics in a bid to ease tensions before and during the global sports event on the peninsula.

North Korean leader Kim Jong-un also shifted to a peace offensive, agreeing to hold summit talks with Moon in late April and US President Donald Trump by May.

Moon is also mulling face-to-face talks with Chinese President Xi Jinping and Japan's Prime Minister Shinzo Abe in the coming weeks to coordinate a strategy on North Korea. Abe reportedly expressed a willingness to meet the North's leader as well.

The national security advisers of South Korea, the US and Japan had an unannounced meeting in San Francisco at the weekend to discuss ways for "complete denuclearization" of Korea, Moon's office Cheong Wa Dae told reporters Monday morning. (Yonhap)