Guam is back in North Korea’s crosshairs after the country fired a missile over Japan.

A successful U.S. test strike against an intermediate-range missile Wednesday raises fresh questions about the feasibility of the U.S. military intercepting a North Korean missile test as a means of deterring the country from future provocative launches. 

But experts say it may not be a practical option since most North Korea missile tests have been aimed at the open seas, including a North Korean missile launched to fly over Japan on Tuesday. The missile defense systems are designed to defend U.S. territory or that of an ally from incoming missiles.

“We don’t have the capability to shoot down every missile every time one is launched,” said David Maxwell, associate director of Georgetown University’s Center for Security Studies. “We have no need to defend the Pacific Ocean.”

Even the missile that crossed Japan, the first such launch, may have been difficult to intercept. It flew nearly 1,700 miles and reached an altitude of 340 miles.

The “lofty” trajectories of some of the recent North Korean launches may complicate efforts to intercept the missiles, said Ian Williams, an analyst at the Center for Strategic and International Studies. 

The high trajectories are useful for North Korea to test the range of its missiles without striking foreign territory, but a missile aimed at a real target would fly on a flatter flight path.

U.S. and allied radar systems can quickly determine where a missile is headed and whether it poses a threat to populated areas. The systems can track test launches also, but there may not be interceptors in a position to shoot them down if they are headed for the open seas.

“Ballistic missiles are…