WASHINGTON — As North Korea hints at new military provocations in the coming days, the United States and South Korea have drawn up plans to respond more forcefully than in the recent past, but in a limited way intended to prevent an escalation to broader war.
Amid the rising tensions, there were still efforts on many fronts on Sunday to limit the possibility of military conflict. In an indirect but clear criticism of China’s longtime ally, North Korea, Xi Jinping, China’s new president, said in a speech on Sunday that no country in Asia “should be allowed to throw a region and even the whole world into chaos for selfish gain.”
A senior adviser to President Obama, Dan Pfeiffer, appearing on the ABC program “This Week,” played down the situation as “a pattern of behavior we’ve seen from the North Koreans many times.”
Still, the escalating tensions were underscored Sunday when the commander of American forces on the Korean Peninsula, Gen. James D. Thurman, abruptly canceled a trip to Washington for Congressional testimony and consultations. So did South Korea’s top commander.
American officials described the new “counterprovocation” plan as calling for an immediate but proportional “response in kind” — hitting the source of any North Korean attack with similar weapons. For example, if the North Koreans were to shell a South Korean island that had military installations, as has occurred in the past, the plan calls for the South to retaliate quickly with a barrage of artillery of similar intensity.
South Korea’s national security director said Sunday that the North this week might launch one of its new Musudan missiles, a modified version of a missile Russia used for decades aboard its submarines. If so, Pentagon officials said they would be ready to calculate its trajectory within seconds and try to shoot it down if it appeared headed toward impact in South Korea, Japan or Guam, an American territory. But they planned to do nothing if it were headed toward open water, even if it went over Japan, as one previous North Korean test did.
The officials doubted that the North’s new leader, Kim Jung-un, would risk aiming the missile at the United States or its allies.
Mr. Obama, officials say, has ruled out striking at the missiles while they are on their launchers — when they are easiest to destroy — unless there is evidence they are being fitted with nuclear warheads, which intelligence officials doubt North Korea yet possesses.
The key, then, is how to respond to anticipated North Korean hostilities while preventing the crisis from escalating.
“How we carry out a proportional retaliation without triggering a general conflict, or an assault on Seoul, is the hardest part of the problem,” said Gary Samore, who served until last month as Mr. Obama’s director for weapons of mass destruction and arms negotiations. “Everyone is aware there are not big margins for error here.”
Some of the public language from the South Korean government suggests that Seoul and Washington may not agree on how far any retaliation should go, although the agreement between the two countries guarantees consultation. “Overreaction by South Korea is a real risk — and we’re working on that problem,” a senior administration official said.
South Korea’s new president, Park Geun-hye, a daughter of a famed South Korean dictator from the cold war, has indicated that she might also go after the North’s command-and-control centers responsible for the provocation.
In the past, classified addendums to the war plan for the Korean Peninsula have not been publicized. So it is notable that agreement on a new plan was publicly disclosed — both to deter the North and to reassure the population of the South. The nature of the response is critical.
Ordering hostilities short of war in an effort to stage-manage the agenda with Seoul and Washington has been a major part of the playbook used by the past two generations of leaders in the North: rapid escalation of a crisis until the United States and South Korea buy temporary peace with aid or investments.
But some American intelligence officials believe that Mr. Kim may have more to gain from striking out at his enemies — within reason — to bolster his credentials with his military, still deeply suspicious of his youth and inexperience.
The absence of a clear understanding about when and how to use force on the peninsula reflects, in part, the rapid shifts over the past 20 years between hard-line South Korean governments and those advocating a “sunshine policy” of reaching out to the North.
Ms. Park was elected on a platform of restarting warmer relations with the government of Mr. Kim, but the rise in tensions has sent her to the other extreme. Under current agreements, the South Koreans remain in command on the peninsula under normal armistice circumstances, but General Thurman, as the commander of American and United Nations forces, would assume operational control if war broke out. The transfer of wartime control is set to transfer to South Korea after 2015.
Ms. Park would be under extraordinary pressure to take action if the North acted out again. When the Cheonan, a South Korean warship, was sunk in March 2010, her predecessor decided not to strike back — and it took months to complete a study that concluded the explosion aboard the ship had been caused by a torpedo shot from a minisubmarine based just over the border in North Korea. Months later, the North shelled a lightly inhabited island in the South — and was met by delayed and ineffective return fire.
“The new agreement defines action down to the tactical level and locks in alliance political consultations at the highest level,” an American official said. The official stressed that the South Korean military would take the lead in any response to hostilities from the North short of war.
“North Korea has gotten away with murder — literally — for decades, and the South Korean and American forces have rarely responded with decisive military action,” said David S. Maxwell, a retired Army colonel who served five tours in South Korea.
“It’s very important to break the cycle of provocation,” said Mr. Maxwell, now the associate director of the Center for Security Studies at Georgetown University. “These responses have to be proportional. They have to be delivered decisively, at the time and at the point of provocation.”
As part of prescheduled military exercises with South Korea, and to prove America’s commitment to regional security, the United States mounted an unusual, highly publicized show of force. It included the decision to use nuclear-capable B-2 bombers, which have a stealthy design to avoid detection, to conduct a mock bombing run in South Korea.