Korea preps for joint exercise with USS Carl Vinson

He did not elaborate amid speculation that the drills will be staged in the East Sea.

Moon would also not go into details on how to respond to North Korea's possible nuclear test.

"It's not appropriate to speak here about that hypothetical question. All I can say is that South Korean and US military authorities are fully prepared for the possibility of North Korea's nuclear test," he said.

Concern has grown that the unpredictable communist country may press ahead with another nuclear test as early as this week, as it is scheduled to celebrate the 85th anniversary of the founding of its armed forces on Tuesday.

US researchers at the 38 North website monitoring the North's activity cited continued activities at its main nuclear test site in Punggye-ri on the basis of commercial satellite imagery dated April 19.

It remains unclear whether the US dispatch of the formidable nuclear-powered flattop close to the North would help discourage it from taking such a provocative act.

Following a round of confusion about its location and mission in the West Pacific, the Vinson is expected here by the end of this week.

The Vinson and other warships in the strike group are currently staging combined drills with Japanese Navy destroyers, according to news reports.

North Korea's state media warned that its troops remain undaunted.

"Our revolutionary forces are combat-ready to sink the US nuclear-powered aircraft carrier with a single strike" to demonstrate their might, the Rodong Sinmun, a newspaper affiliated with the North's ruling Workers' Party, said in a commentary.

The Donald Trump administration issued a terse response to the threat.

"We call on (North Korea) to refrain from provocative, destabilizing actions and rhetoric, and to make the strategic choice to fulfill its international obligations and commitments and return to serious talks," Pentagon spokesman Gary Ross sad. (Yonhap)