Even so, the question is whether the broader diplomatic policy that Obama’s aides have dubbed “strategic patience” – which seeks to isolate North Korea and not offer diplomatic rewards for its provocations – can meet the challenge of what has become one of the most serious crises on the peninsula since the end of the Korean War in 1953. …

U.S. and South Korean forces would do nothing if, as they expect, the missile heads for open water. But they would be ready to shoot it down if it threatens South Korea, Japan or the U.S. territory of Guam, another administration official said.

U.S. officials have not ruled out the possibility, however, that North Korea could instead carry out a strike on a South Korean ship or border post. This would trigger “proportional retaliation” by South Korea, though precautions have been put in place in hopes of avoiding escalation into open conflict, they said.

The new security arrangement, first reported by the New York Times on Monday, is meant to reassure South Korea – which restrained itself after being caught off guard by a pair of North Korean attacks in 2010 – that it would have room to respond militarily to any new provocation. …

Even as tensions rise and the Obama administration adjusts accordingly, it is showing no signs of abandoning its “strategic patience” approach altogether.

“What’s important is we not allow North Korea to profit one iota from this situation,” the senior official said.