The United States has warned that it would be “unwise” for North Korea to make good on its threat to seek a "physical response" to planned U.S.-South Korean naval exercises.

State Department spokesman Philip Crowley stressed to reporters Friday that the planned exercises are defensive in nature and reflect the importance of the U.S. alliance with South Korea. He added that it would not be “fruitful” for North Korea to increase tensions in the region at this point.

Crowley also said that if Pyongyang takes affirmative steps toward denuclearization and commits to better relations with its neighbors, then diplomatic opportunities could potentially open up.

U.S. Secretary of State Hillary Clinton hinted during the ASEAN Regional Forum in Hanoi earlier this week that the U.S. is willing to discuss normalizing relations with the North if it changes its behavior and the Korean Peninsula becomes nuclear-free.