The military is still trying to confirm details, including the type of projectile and whether the missile blew up midair or not.

The US defense authorities said the North's missile seems to have exploded shortly after takeoff.

The US Pacific Command said it detected what it assesses was a "failed North Korean missile launch attempt" from an area in the vicinity of Kalma, Gangwon Province.

"A missile appears to have exploded within seconds of launch," it said. "We are working with our interagency partners on a more detailed assessment. We continue to monitor North Korea's actions closely."

The North's provocation came as the US has sent a set of key strategic defense assets here, such as an aircraft carrier and a nuclear-powered submarine, for the Foal Eagle and the Key Resolve drills.

The Donald Trump administration made it clear that it would deal resolutely with a provocative North Korea.

During a visit to Seoul last week, Secretary of State Rex Tillerson warned that all options are being considered.

Meanwhile, senior South Korean and US diplomats handling North Korea issues -- Kim Hong-kyun and Joseph Yun -- had talks in Seoul on Wednesday.

Earlier this month, the North fired four ballistic missiles, three of which fell into the sea near Japan. (Yonhap)