The ruling party chief on Monday renewed calls for North Korea to return to dialogue, saying the reduced number of American troops in the ongoing South Korea-US military exercise should be construed as Washington's desire for talks.

Earlier in the day, the allies began the annual Ulchi Freedom Guardian exercise set to run through Aug. 31 with the participation of some 17,500 US service members, down from 25,000 last year. Pyongyang has criticized it as a "rehearsal for an invasion."

"I hope that rather than just criticizing the drills, the North will take (the reduced level of US troops) as a signal for Washington-Pyongyang talks," Choo Mi-ae, the leader of the Democratic Party, said during a meeting with senior party members.

Choo Mi-ae, the leader of the ruling Democratic Party, speaks during a meeting with senior party officials at the National Assembly in Seoul on Aug. 21, 2017. (Yonhap)
"I also hope the North would not make a reckless choice to engage in another provocative act by misjudging the situation," she added.

Choo also pointed out that the North's "dangerous" nuclear brinkmanship would not work in the face of the international community's opposition to it.

Pyongyang has so far shown no interest in Seoul's overtures for cross-border talks, posing a tricky challenge to President Moon Jae-in's peace initiative that aims to address the long-standing nuclear standoff based on sanctions and dialogue.

Meanwhile, US Defense Secretary Jim Mattis rejected the notion that the cut in the number of US troops in the allied exercise was caused by escalating tensions with the provocative regime. He said that the exercise had been planned months in advance.

"The numbers (of troops) are by design to achieve the exercise objectives, and you always pick what you want to emphasize," Mattis told reporters en route to Jordan, according to a transcript released by his office. "Right now, there is a heavy emphasis on command post operations, so the integration of all the different efforts." (Yonhap)