President Donald Trump is taking a "big step" toward nuclear war by seeking a naval blockade, North Korea's state news agency KCNA said Thursday, according to Reuters.

It said the possibility of a naval blockade, a sanction proposed by the U.S. as a response to North Korea's launching of intercontinental ballistic missiles and nuclear tests, was a "violation of its sovereignty and dignity" and that it would take "merciless self-defense measures" against the blockade, which it sees as an act of war.

Tensions are running high between North Korea and the West, especially the U.S., after the Communist regime of North Korea launched what was believed to be another intercontinental ballistic missile in late November.

North Korea said at the time that it was capable of reaching the U.S. mainland. It has also claimed that it has been able to attach a nuclear warhead to its missiles, although this has not been independently verified.

The U.S. and Western nations condemned the launch and implemented further sanctions on North Korea. Secretary of State Rex Tillerson also announced then that a naval blockade could be imposed.