U.S. State Department spokesman Philip Crowley said Thursday that North Korea's threats of a "sacred war" using its arsenal of nuclear weapons are without justification.

"We've heard this language before," said Crowley in an interview on the BBC's Newshour. "Unfortunately sometimes that kind of language is followed by irresponsible actions, whether it's a missile test, a nuclear test or the shelling of South Korea, as occurred last month."

North Korea fired on South Korea last month, killing four people and prompting South Korea to begin mlitary exercises.

Tension began to heighten between the two countries after a South Korean warship was sunk earlier this year.

Read more about what Crowley had to say here.