The U.S. is beefing up its presence around the Korean Peninsula ahead of next month's Winter Olympics by deploying stealth bombers, at least one extra aircraft carrier and a new amphibious assault ship to the region.

Coming after Washington agreed to postpone massive annual military manoeuvres with South Korea until after the Games, North Korea says the U.S. is trying to put a chill on its renewed talks with Seoul.

"Such moves are an unpardonable military provocation chilling the atmosphere for improved inter-Korean relations," the North's ruling party said in a commentary published over the weekend.

Representatives of both Koreas held a second round of talks Monday near the Demilitarized Zone to try to pave the way for a North Korean delegation to join the Pyeongchang Games.

The U.S. has officially welcomed the talks, and the moves represent routine training and scheduled upgrades, according to U.S. military officials.

Tensions remain high and the military deployments are significant.

Last week, the Pacific Air Forces announced three B-2 "Spirit" stealth bombers with approximately 200 personnel have been deployed from Whiteman Air Force Base in Missouri to the Pacific island of Guam.

The nuclear-powered USS Carl Vinson aircraft carrier leaves San Diego Bay for deployment to the western Pacific, in San Diego, on Jan. 5. (Gregory Bull/Associated Press)

The statement said the deployment is intended to provide leaders with "deterrent options to maintain regional stability."

But the Guam deployment hits an especially sore nerve and plays on a key vulnerability for Pyongyang, which is probably the message Washington had in mind as it seeks to make sure nothing happens during the Olympics and also let Pyongyang know its decision to postpone the exercises is not a sign of weakness.

'Deterrent options'

Last year, flights by B-1B bombers from Guam to the airspace around Korea were a major flashpoint, prompting a warning from North Korea that it had drawn up a plan to target the waters around the island with a missile strike that it could carry out anytime Kim gave the order.

The B-2 is more threatening.

It's the most advanced bomber in the Air Force and, unlike the B-1B, can carry nuclear weapons. It's also the only known aircraft that can drop the Air Force's biggest bomb, the 14,000-kilogram GBU-57 Massive Ordnance Penetrator.

The "MOP," capable of penetrating deep into the ground to destroy reinforced tunnels and bunkers, was explicitly designed with North Korea in mind.

The B-2 deployment came just days after the USS Carl Vinson aircraft carrier departed for the western Pacific in what the Navy called a regularly scheduled deployment. South Korean media reports say the carrier and its strike group will reach waters near the Korean Peninsula ahead of the start of the Games on Feb. 9.

The USS Ronald Reagan aircraft carrier, whose home port is just south of Tokyo in Yokosuka, is also in the region, and North Korea has accused the U.S. of planning to send another carrier, the USS John Stennis from Bremerton, Washington.

Such moves are an unpardonable military provocation chilling the atmosphere for improved inter-Korean relations. - North Korea ruling party

The marines announced on Sunday the arrival in southern Japan of the USS Wasp, an upgraded amphibious assault ship that can carry troops and launch the corps' new F-35B stealth fighters. It can carry 30-plus aircraft, including the F-35s, which are designed for vertical takeoffs and landings.

The ships and bombers could figure largely in a U.S. response to any military emergencies during the Winter Games. North Korea may view them as a greater and more imminent threat.

Aircraft carriers, virtually impervious to any attack the North could mount, are floating platforms for sustained air assaults, while the F-35 fighters could be a key part of any potential strike on Kim Jong-un himself.