US Defense Secretary Lloyd Austin has "no plans" to visit South Korea "at this time," an official said Thursday, following a report that he scrapped a plan to travel to the Asian country in the aftermath of President Yoon Suk Yeol's short-lived martial law imposition.

The move came amid concerns that despite Washington's renewed commitment to the "rock-solid" alliance, a period of uncertainty in South Korea could affect coordination between the allies over North Korea's security challenge and other key issues.

Seoul and Washington also postponed a session of the Nuclear Consultative Group, the allies' key nuclear deterrence talks, and a related exercise originally slated for earlier this week, according to a Pentagon spokesperson.

"There are no plans for Sec. Austin to visit the Republic of Korea at this time," a US defense official told Yonhap News Agency via email.

Earlier in the day, Reuters reported, citing sources, that planning had been underway for Austin's trip to Seoul "in the near term" but it was determined now was not the "appropriate time.

During a press briefing, Pentagon press secretary Maj. Gen. Pat Ryder said that Austin will travel to Japan in his 13th visit to the Indo-Pacific in his capacity as a secretary, but no plan to visit Korea was mentioned.

"(The trip) comes as the department continues its historic efforts to bolster our partnerships and alliances and advance a shared vision of peace, security and prosperity in the region," Ryder said.

Following the surprise martial law declaration on Tuesday night, US officials have expressed "grave concern," though they showed a sense of relief later over Yoon's reversal of the emergency decree, and underscored the resilience of South Korea's democracy. (Yonhap)