The U.S. Missile Defense Agency announced that it tested a ground-based interceptor system last weekend. Inhofe, R-Okla., ranking member of the Senate Armed Service Committee, said the test was vital for national security given recent threats from North Korea.
"Our intelligence agencies have discovered that North Korea is moving mobile missile launchers around the country where they can be hidden," he said in a statement. "This clearly suggests the ballistic missile threat to the United States is becoming more complicated."
Satellite imagery from North Korean military installations last week suggests Pyongyang is preparing to test a nuclear device. North Korea in December fired a long-range rocket and similar launches in 2006 and 2009 coincided with nuclear tests.
Inhofe expressed concern about funding for missile defense given threats from rogue regimes like Iran and North Korea.
Russia has said it wants assurances that U.S. plans for a missile defense shield in Europe won't target its strategic interests.