WASHINGTON — Despite a drumbeat of increasingly bellicose threats from North Korea, the White House said Monday that there was no evidence that the country’s leader, Kim Jong-un, was mobilizing troops or other military forces for any imminent attack.
Though American officials said they remained concerned about the invective flowing from North Korea — and South Korea’s president ordered military commanders to carry out a swift and strong response to any provocations — the Obama administration took pains to emphasize the “disconnect” between Mr. Kim’s “rhetoric and action.”
The White House’s strategy, officials said, was calculated to ease tensions after a fraught few days in which Mr. Kim threatened to rain missiles on the American mainland and the United States responded by flying nuclear-capable bombers over the Korean Peninsula.
“We are not seeing changes to the North Korean military posture such as large-scale mobilizations or positioning of forces,” said Jay Carney, the White House press secretary. “What that disconnect between rhetoric and action means, I’ll leave to the analysts to judge.”
Even as the White House tried to tamp down the tensions, the Pentagon said it had moved a Navy missile-defense ship from its home port in Japan to waters closer to the Korean Peninsula, in what was described as a carefully calibrated response, given the North’s warnings about putting its rockets on a higher stage of alert.
The deployment came after the United States publicized a rare training flight by two B-2 bombers over South Korea, where they carried out a mock bombing run, and pledged to spend $1 billion to expand ballistic missile-defense systems along the Pacific Coast.
Having taken these unusually public steps to demonstrate its commitment to defend itself and protect South Korea and Japan, the Obama administration appeared to be trying to defuse a situation that many analysts say has gone beyond previous cycles of provocation by North Korea, and raised genuine fears of war.
“It is a calculated response to say, ‘We don’t want anyone to think the situation is getting out of control, that the ladder of escalation is going to end in a full-scale conflict,’ ” said Jeffrey A. Bader, who worked on North Korea policy for the Obama administration from 2009 to 2011.
For all the uncertainty surrounding the young ruler of North Korea, Mr. Bader said, the latest round of warlike statements from the North recalled the theatrical belligerence shown by Mr. Kim ’s father, Kim Jong-il. Those episodes often led to hostile acts, but never a wholesale military attack on South Korea.
Still, on Monday, South Korea’s new president, Park Geun-hye, ordered her country’s military to deliver a strong and immediate response to any North Korean provocation.
“I consider the current North Korean threats very serious,” Ms. Park told the South’s generals. “If the North attempts any provocation against our people and country, you must respond strongly at the first contact with them without any political consideration.”
Ms. Park’s blunt comments contrasted with the usually dismissive tone that South Korean leaders take toward the North’s threats, and reflected the criticism directed at her predecessor, Lee Myung-bak, when the South was seen as not retaliating after North Korea aimed an artillery barrage at a South Korean island in 2010, killing four people. Ms. Park’s election campaign last year focused on a promise not to be blackmailed by the North.
Since Kim Jong-un took power in late 2011, the North has launched a three-stage rocket, tested a nuclear device and threatened to hit major American cities with nuclear-armed ballistic missiles. The Korean Peninsula, Mr. Kim declared, has reverted to a “state of war.”
His actions, analysts say, reflect the North’s growing frustration that its strategy of using threats and provocations against the United States and South Korea seemed less effective in recent years. Instead, the allies spearheaded another round of United Nations sanctions.
The imposition of the sanctions coincided with the allies’ joint military drills, during which Washington publicized the training missions of B-52 and B-2 bombers, as well as F-22 stealth fighter jets. Washington also concluded three years of negotiations with Seoul and signed an agreement last week to respond jointly to North Korean provocations. The move was intended to bolster deterrence against the North and to prevent unnecessary escalation.
The American vessel recently deployed to waters off the Korean Peninsula, an Aegis cruiser, will remain there “for the foreseeable future,” said a Defense Department official. Two ballistic-missile ships, which carry powerful tracking radars and interceptor missiles, had been in the area for a recent joint exercise with the South Korean military, but they had returned to Japan after that exercise ended.
While analysts generally praise the administration’s handling of the latest tensions, Joel S. Wit, a former State Department official who worked on North Korea, said, “It’s starting to feel like we send a new airplane to South Korea every day to prove our resolve.”
Mr. Wit said that Washington needed to explore diplomatic channels to North Korea as well, not least because President Park had signaled her intent to pursue diplomacy with the North — perhaps even without insisting that Pyongyang renounce its nuclear weapons as a precondition for talks. There is a risk that the United States could find itself out of sync with its ally, Mr. Wit said.
But Michael J. Green, a North Korea policy adviser in President George W. Bush’s administration, said that given the lack of success in curbing North Korea’s nuclear and missile programs, the White House had little choice but to pursue a strategy that resembled containment, even if no official would ever use that phrase.
“The focus for the near future has to be on deterring North Korea,” Mr. Green said, “punishing them for violations, and constraining their ability to move their nuclear program forward or proliferate.”
Mark Landler reported from Washington, and Choe Sang-hun from Seoul, South Korea. Thom Shanker contributed reporting from Washington.
This article has been revised to reflect the following correction:
Correction: April 1, 2013
An earlier version of this article misstated the American military’s designation for the stealth fighter jets that are taking part in joint training missions with South Korea. It is F-22, not B-22.