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Pentagon spokesman Navy Captain Jeff Davis said a routine test of the Terminal High Altitude Area Defense (THAAD) system had been scheduled to go ahead "soon".
"These tests are done as a routine measure to make sure that the system is ready," he said.
"They are scheduled well in advance of any other real world geopolitical events going on."
A notice to mariners put out by the US Coast Guard said the test could occur as soon as Saturday.
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 ICBM -- that job is left primarily to the Ground-based Midcourse Defense (GMD) interceptor system.
Missile Defense Agency Director Lieutenant General Sam Greaves said in a statement the test would occur at the Pacific Spaceport Complex, Alaska.
"Due to the need to safeguard critical defense information, the (Defense) Department will not provide test details in advance beyond the required safety notifications," he said.
The military earlier this month 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 intercontinental ballistic missile capable of reaching parts of the United States -- including Alaska.