The Pentagon said Monday that it plans to participate in new military exercises with South Korea, the first direct military response from the United States to the sinking of a South Korean warship by what officials called a North Korean torpedo.
Bryan Whitman, the Pentagon spokesman, said U.S. forces will participate in an anti-submarine maneuver in "the near future." In a second planned exercise, U.S. units along with South Korea and possibly other regional allies will work to improve their ability to interdict cargo ships carrying arms or other prohibited materials to or from North Korea.
The exercises were announced Monday in Seoul by the South Korean Defense Ministry, following a nationwide address by President Lee Myung-bak in which he ordered a halt to most trade with the North, and closed all sea lanes between the nations.
Later Monday, U.N. Secretary-General Ban Ki-moon further intensified pressure on North Korea by declaring in New York that "there must be some measures taken" to respond to what officials consider the North's attack. Ban, speaking at a news conference, didn't specify the steps.
An international investigation has held North Korea responsible for the sinking of the Cheonan, a South Korean naval vessel, on March 26. The apparent attack killed 46 South Korean sailors and represented what South Korean and U.S. officials consider a violation of the armistice between Pyongyang and Seoul that ended the Korean War of the 1950s.
A growing international demand for a response is exerting pressure on a reluctant China, North Korea's most important ally, to support consideration of the issue by the U.N. Security Council.
U.S. and South Korean officials are meeting with the Chinese this week to try to convince them to agree to Security Council deliberations. Secretary of State Hillary Rodham Clinton appealed to Chinese officials in Beijing on Monday, but met resistance, officials said.
Though North Korea has denied it authorized a strike against the South Korean ship, the upcoming anti-submarine exercise appears aimed at warning Pyongyang against any future attacks. The maritime interdiction exercise, as it is known, will hone efforts to halt weapons shipments.
Whitman said the exercises were a sign of the "continuation of a very strong, closely coordinated relationship" with South Korea. He said the two events were scheduled specifically in response to the apparent attack on the warship.
There are approximately 28,000 U.S. troops stationed in South Korea.
Analysts said South Korea is trying to reestablish conventional military deterrence on the Korean peninsula by taking the strongest measures it can, short of military action.
Victor Cha, a White House advisor on Korea during the George W. Bush administration, noted that the South Korean leader in his speech took the unusual step of drawing a "red line" for North Korea by declaring that his nation would not tolerate another such act.
"The danger is, the North may cross it," said Cha, now with Georgetown University.
U.S. and South Korean officials want to make a point to Pyongyang with the exercises, but also want to avoid a violent reaction. North Korea has threatened war if South Korea retaliates.
Clinton said in comments to reporters that the United States was "working hard to avoid an escalation of belligerence and provocation."
South Korea's Yonhap news agency reported that North Korea put its military on combat footing early Tuesday, Reuters said.
U.S. military officials, meanwhile, are watching for the possibility of North Korean nuclear and missile tests, especially over the Memorial Day holiday. Pyongyang has conducted previous tests around U.S. holidays. Tuesday marks the anniversary of a North Korean nuclear test last year.