"Well, we are certainly concerned by North Korea's bellicose rhetoric," Carney said during his media briefing. "And the threats that they have been making follow a pattern designed to raise tension and intimidate others."
North Korea "will achieve nothing by threats or provocations, which will only further isolate North Korea and undermine international efforts to ensure peace and stability in Northeast Asia," Carney said.
North Korea has taken a more strident position on the U.N. Security Council adoption of a new round of sanctions in response to the reclusive country's third nuclear test last month. North Korea also said it nullified the 1953 cease-fire to the Korean War and threatened a pre-emptive nuclear strike against South Korea and the United States.
The pitched rhetoric began in advance of joint U.S.-South Korea military drills Monday.
"We continue to urge the North Korean leadership to heed President Obama's call to choose the path of peace and come into compliance with its international obligations," Carney said. "We have worked in a concerted way with our international partners to put pressure on and isolate North Korea because of its failure to live up to its obligations."
In Seoul, new South Korean Foreign Minister Yun Byung-se said tensions between North and South Korea are creating a "very grave" security situation.
Yun said his goal is to "turn this era of confrontation and mistrust into an era of trust and cooperation with North Korea," Yonhap reported.
"The security situation on the Korean Peninsula for now is very grave as the unpredictability surrounding North Korea is rising following its third nuclear test," Yun said in his first address since becoming foreign minister.
North Korea also cut off a Red Cross hotline with South Korea earlier Monday as South Korea and the United States began their annual military drills, Yonhap said. The two-week computer-simulated exercise, called Key Resolve, mobilizes 10,000 South Korean forces and 3,500 U.S. military personnel.
South Korea will seek a dialogue with North Korea despite rising tensions, Seoul's new unification minister said Monday.
In his inaugural address, Ryoo Kihl-jae stressed that inter-Korean talks are necessary despite the gravity of the current situation.
"Holding talks is critical, and it is vitally important that both Koreas respect and adhere to past agreements such as the July 4th North-South Joint Statement signed in 1972, the June 15 Joint Declaration reached in 2000 and the Oct. 4 joint declaration agreed to in 2007," he said.
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