WASHINGTON — The United States is flying B-52 planes on training missions over South Korea to highlight Washington’s commitment to defend an ally amid rising tensions with North Korea, Pentagon officials said Monday.
Pentagon press secretary George Little said one B-52 flew over South Korea on March 8. And Deputy Defense Secretary Ashton Carter, who is visiting Seoul, said another bomber mission is scheduled for Tuesday.
B-52 planes are capable of launching nuclear-armed cruise missiles, but Little said those participating in the Korean exercise are not armed with nuclear weapons.
The use of Air Force warplanes as part of an annual US-South Korean military exercise called Foal Eagle is not unusual.
But the Pentagon used the occasion to draw attention to the role B-52s play as part of an American nuclear ‘‘umbrella’’ over South Korea and Japan — both of which feel threatened by North Korea’s development of nuclear weapons and ballistic missiles.
‘‘We’re deeply concerned about North Koreans’ behavior and rhetoric,’’ Little told reporters.
In Seoul on Monday, Carter warned North Korea over its recent threats and reassured South Korea that America’s military commitment will not be hurt by the US budget crisis.
Carter told reporters that South Korea defense is a priority and Pyongyang’s threats would only deepen Washington’s defense commitment to Seoul.
He said that includes the nuclear security guarantee for Seoul, which doesn’t have atomic weapons.
Pyongyang is angry over US-South Korean war games and UN sanctions meant to punish it for its third nuclear test.
It has threatened nuclear attacks on Washington, though it is not believed to have the weapons needed to do so.
Carter said he discussed with South Korean officials the North’s ‘‘continued pattern of provocative actions.’’
In a separate development Monday, China said the US decision to strengthen missile defenses on the Pacific Coast in response to threats from North Korea risked deepening tensions in the region.
Defense Secretary Chuck Hagel on Friday announced that the United States is beefing up its defenses against a potential North Korean missile attack on the United States.
Earlier this month, China backed a UN Security Council resolution imposing banking, trade and travel sanctions on North Korea after it held a third nuclear test, on Feb. 12.
Chinese Ministry of Foreign Affairs, Hong Lei, told reporters in Beijing that the antimissile deployments “can only deepen antagonism and will be of no help to solving problems.’’ Hong did not mention Hagel or the United States by name, but his meaning was clear.
Hagel said that over the coming four years the Pentagon will add 14 missile interceptors to the 26 it already has in place at Fort Greely, Alaska, at an estimated cost of $1 billion.
Hagel cited three recent developments in North Korea that prompted the Obama administration to act, including the nuclear test in February.
Hagel also cited Pyongyang’s launch in December of a rocket that put a satellite into space and demonstrated mastery of some of the technologies needed to produce a long-range nuclear missile.
And he noted that last April the North Koreans put on public display a road-mobile intercontinental ballistic missile, the KN-08.
Admiral James Winnefeld Jr., vice chairman of the Joint Chiefs of Staff, said that missile is believed to be capable of reaching US territory.
Although not mentioned by Hagel, North Korea raised tensions further by threatening last Thursday to preemptively attack the United States.