WASHINGTON (AFP) - The US military is preparing to conduct another test of a missile-intercept system in Alaska, the Pentagon said on Monday (July 24), amid continued tensions with North Korea over its ballistic missile programme.

Pentagon spokesman, Navy Captain Jeff Davis, said a routine test of the Terminal High Altitude Area Defence (Thaad) system had been scheduled to go ahead "soon".

He said: "These tests are done as a routine measure to make sure that the system is ready. They are scheduled well in advance of any other real world geopolitical events going on."

A notice to mariners put out by the United States Coast Guard said the test could occur as soon as Saturday (July 29).

Thaad is designed to intercept and destroy short-, medium- and intermediate-range ballistic missiles during their final phase of flight.

Thaad is not designed to stop an intercontinental ballistic missile (ICBM) - that job is left primarily to the Ground-based Midcourse Defence (GMD) interceptor system.

Missile Defence Agency Director, Lieutenant-General Sam Greaves, said in a statement that the test would occur at the Pacific Spaceport Complex, Alaska.

"Due to the need to safeguard critical defence information, the (Defence) Department will not provide test details in advance beyond the required safety notifications," he said.

The military earlier this month (July) successfully tested Thaad against an intermediate-range target, the first successful trial against that type of missile.

Though such exercises are planned months in advance, it came after North Korea's first-ever test-firing of an ICBM capable of reaching parts of the US, including Alaska.