The White House said Monday the deployment of advanced warplanes such as B-2 bombers and F-22 stealth fighters to the Korean Peninsula has helped decrease the possibility of a North Korean miscalculation or provocation.

"We believe this has reduced the chance of miscalculation and provocation," press secretary Jay Carney said at a press briefing.

The U.S. has not seen any unusual military action by North Korea despite its near-daily threats to attack the U.S. and its regional allies, he added.

"We haven't seen action to back up the rhetoric in the sense that we haven't seen, you know, significant changes in the North in terms of mobilizations or repositioning of forces, and that is important to note," Carney said.

With annual joint military drills with South Korea under way, the U.S. briefly deployed Japan-based F-22 Raptor stealth fighters to Korea after sending B-52 Stratofortress and B-2 Spirit bombers, both of which are capable of carrying nuclear bombs.

In a rare move, the U.S. military made public the dispatch of those strategic weapons.

In a separate press briefing, Pentagon spokesman George Little confirmed two F-22s from the 94th Expeditionary Fighter Squadron, based at Kadena Air Base, Japan, deployed to Osan Air Base, on Sunday (local time), marking the fourth time the F-22 has deployed to South Korea.

"The aircraft are on static display at Osan Air Base as part of the Foal Eagle exercise to provide bilateral training for the U.S. and ROK military and to provide South Korean senior leaders with an orientation to the aircraft, which are an advanced capability that is available for the defense of South Korea," he said.

Critics said the U.S. move has contributed to escalating tensions as the North responded angrily to it.

But the White House official said it was an important step to "reassure our allies, demonstrate our resolve to the North and reduce pressure on Seoul to take unilateral action."

The U.S. is apparently concerned about the possibility that the tensions on the peninsula will get out of control and trigger another major conflict.

South Korean President Park Geun-hye ordered the military Monday (local time) to deal sternly with any North Korean provocation without "political considerations."

The State Department reiterated Washington takes Pyongyang's threats very seriously and it would remain vigilant.

It pointed out that the door is still open for diplomacy.

"We've made clear that there is a chance for diplomacy if they do the right thing but not if they don't," department spokeswoman Victoria Nuland told reporters.

She emphasized that President Barack Obama has been clear that if North Koreans "unclench their fists," the U.S. is willing to meet them.

"These kinds of threats are not going to get them back to the table," she said. "They're going to take them in the opposite direction."

The North Korea crisis will be high on the agenda when Secretary of State John Kerry travels to Seoul, Tokyo and Beijing next week.

Kerry is also scheduled to hold one-on-one talks with his South Korean counterpart, Yun Byung-se, in Washington on Tuesday.

South Korea's top nuclear envoy, Lim Sung-nam, met here Monday with Glyn Davies, the U.S. special representative for North Korea policy, for discussions on ways to deal with North Korea. (Yonhap News)