North Korea said its latest missile test was meant to bolster Pyongyang’s “fatal” nuclear attack capabilities, after U.S. officials denounced the tests and announced joint military exercises with South Korea and Japan.

The “sudden” missile test last week, as reported by North Korea’s official Korean Central News Agency, was also meant to showcase the country’s “powerful physical nuclear deterrent.”

It was the first intercontinental ballistic missile test by North Korea since the beginning of the year. The U.S. responded on Sunday by flying bombers in a joint exercise with South Korea.

U.S. officials blasted North Korea over its launch, which saw the missile land in the Sea of Japan, arguing the test “needlessly raises tensions.”

“This launch needlessly raises tensions and risks destabilizing the security situation in the region,” National Security Council spokesperson Adrienne Watson said. “It only demonstrates that the DPRK continues to prioritize its unlawful weapons of mass destruction and ballistic missile programs over the well-being of its people.”

According to the KCNA, the missile flew at a steep angle and traveled about 650 miles, meaning it could theoretically reach the mainland U.S. if fired at a more standard angle. But debate still rages over whether the country has functional nuclear-tipped missile capabilities.

The response from the U.S. and its Asian allies included South Korean and American fighter jets escorting American B-1B bombers, which alarm North Korea because of their ability to carry a large load of conventional weapons.

North Korea launched over 70 ballistic missiles last year.