North Korea’s ballistic missile test is shining an intense spotlight on the Pentagon’s missile defenses, systems installed to protect South Korea and now the U.S. mainland. Recent results have been promising, but U.S. officials acknowledge that Pyongyang’s stunning advances this month are providing a real-world test much sooner than they had expected. The Pentagon has been touting the viability of the country’s ballistic missile systems following the apparent successful test by the regime of Kim Jong-un of a long-range missile on July 4, saying the constellation of missile interceptors and weapons now in place are fully capable of blocking any threat to American shores from Pyongyang or elsewhere. The need for reliability of the missile defense systems, including the new Terminal High-Altitude Area Defense (THAAD) missile defense battery installed in South Korea, soared amid calculations that the North has tested what could be its first intercontinental ballistic missile. In what Pentagon officials insisted was a previously planned exercise, the U.S. Missile Defense Agency revealed Tuesday that a THAAD system based in Alaska successfully tracked and shot down a simulated intermediate-range ballistic missile that closely resembles the ones Pyongyang is developing. The test was the first of its kind for the system against an incoming intermediate-range missile, which analysts say is harder to hit than shorter-range missiles. “This test further demonstrates the capabilities of the THAAD weapon system and its ability to intercept and destroy ballistic missile threats,” Lt. Gen. Samuel A. Greaves, director of the Missile Defense Agency, said in a statement. Sen. Dan Sullivan, an Alaska Republican whose state suddenly finds itself potentially in range of Pyongyang’s deadliest weapons, praised the test. He said it “provided further confirmation that we have the capability to defend our bases, our troops and our allies in places like Japan, South Korea and Guam against rogue nations like North Korea.” But any test falls far short of real-world conditions, when the enemy doesn’t reveal in advance where and when the missile will be launched or its intended target. “Missile defense, even if it worked perfectly, is not a get-out-of-jail-free card,” Laura Grego, a senior scientist for the Global Security Program at the Union of Concerned Scientists, told the Bloomberg news service. Missile defense systems, critics note, can’t afford to have a single failure against powerful payloads likely to be loaded onto an ICBM. “The homeland missile defense system doesn’t work perfectly and hasn’t demonstrated a real-world capability,” Ms. Grego said. Even before the July 4 test, the Pentagon was poised to invest billions of dollars to boost its anti-missile technology as part of President Trump’s first defense budget. Aside from additional funding, Defense Department officials are spearheading an overhaul of missile defense strategies and tactics. In one of his first acts as Pentagon chief, Defense Secretary James Mattis initiated a departmentwide review of missile defense operations in May. The review, led by Deputy Secretary of Defense Robert O. Work and Vice Chairman of the Joint Chiefs of Staff Gen. Paul J. Selva, will “identify ways to strengthen missile defense capabilities, rebalance homeland and theater defense priorities, and provide the necessary policy and strategy framework for the nation’s missile defense systems,” Pentagon press secretary Dana White said. The administration’s newfound focus on the network of land- and sea-based interceptor weapons and associated sensors comes on the heels of the first successful test of the Pentagon’s premier missile interceptor system in May. The game-changer in the debate was the successful July 4 test of the Hwasong-14 intercontinental ballistic missile, which flew higher and farther than any previous North Korean long-range missile shots, theoretically placing the entire state of Alaska within range of Pyongyang’s new class of ballistic missiles.