The U.S. says it will not hesitate to pursue actions that deliver a strong message to North Korea in relation to the North’s sinking of the “Cheonan.” The U.S. will look to see how it can influence North Korean thinking and, most importantly, North Korean behavior.

State Department spokesman Philip Crowley made the remarks Wednesday, shortly after the North announced it was cutting all ties with South Korea.

Crowley said he can’t imagine a step that is less in the long-term interest of the North Korean people than cutting off further ties with South Korea.

He said that there are things that the U.S. can do unilaterally in terms of economic measures as a means to pressure the North. He said Washington is working closely with its regional partners to see what can and should be done to have the greatest impact on the North Korean leadership.