In his remarks, Trump promised an expansive and likely impossible system that harked back to Reagan’s initial goal of rendering missiles essentially obsolete with technologies that would intercept and destroy them.

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“The system will be monitored, and we will terminate any missile launches from hostile powers or even from powers that make a mistake,” Trump said. “It won’t happen, regardless of the missile type or geographic origins of the attack.”

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But the Pentagon stopped far short of those towering goals in the Missile Defense Review it released Thursday. The first comprehensive update to U.S. missile defense policy in nine years, the review pushed to expand the scope and sophistication of American missile defenses but didn’t set out plans that would achieve the Cold War-era vision.

The Pentagon added hyper­sonic weapons and cruise missiles to the list of systems the military wants to be able to shoot down and proposed a range of new options to counter North Korean missiles. It approved a constellation of sensors in space aimed at “birth-to-death tracking” of missile launches and called for studies of lasers and space weapons to intercept missiles.

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The review expanded the mission of U.S. missile defense beyond countering “rogue states” such as North Korea and Iran to protecting U.S. forces and allies in Europe and Asia against regional threats posed by Russia and China.

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It didn’t, however, recommend what Trump described. That’s because the Pentagon has long recognized that a full-scale nuclear missile attack on the United States from a peer adversary such as Russia would overwhelm the limited missile defenses the military has built.

To deter such a full-scale attack, Washington relies on the promise of mutually assured destruction guaranteed by its nuclear arsenal, not on missile defenses. The missile interceptors the U.S. military operates in Alaska and California are designed to down a limited number of missiles launched by rogue states.

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“There was some gesture toward a global comprehensive missile defense system in the president’s remarks — that we would counter any missile, any time, from anywhere,” said Laura Grego, a senior scientist at the disarmament group Union of Concerned Scientists. “That’s just technically unachievable and economically ruinous if you tried.”

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Though the missile defense review didn’t entirely jibe with the president’s remarks, it marked what Undersecretary of Defense for Policy John Rood, a former defense industry executive, described in a briefing as “the start of a new era, the next era, in missile defense.”

Whether any of the plans will come to pass depends on whether the Pentagon can secure increases in missile defense spending from Congress and whether the Defense Department prioritizes missile defense over other investments. Rood declined to say whether the upcoming budget request for missile defense would increase significantly.

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The Pentagon presented the plan as a necessary step because of the proliferation of missile threats around the globe, including North Korea’s tests of intercontinental ballistic missiles that can hit the United States and Russian and Chinese advances in hypersonic glide vehicles that can travel many times the speed of sound. The United States currently does not have any systems designed to track and stop those vehicles.

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Acting Defense Secretary Patrick Shanahan, who helped manage Boeing’s missile defense program before arriving at the Pentagon, said competitors, including Russia and China, are not only advancing their missile capabilities but also integrating them into political intimidation efforts and war plans.

“Writ large, the rest of the world is not developing new fighter and bomber aircraft,” he said. “They are developing missiles.”

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Supporters of more robust missile defense welcomed the high-profile endorsement from the president and the Pentagon plans. Critics, who have long said missile defense systems waste money and work poorly, expressed relief that the review didn’t mandate some controversial initiatives, such as space weapons to shoot down missiles, and instead called for studies.

The review proposes investments in new technologies that could help the United States bolster defenses against North Korean missiles. It suggested modifying the F-35 fighter jet to shoot down ballistic missiles and possibly mounting lasers on drones that could track and destroy missiles shortly after their launch.

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The review also said the Pentagon is planning to test an adaptation of Aegis missile interceptors on ships so they can down intercontinental ballistic missiles in addition to the short and intermediate-range ballistic missiles they target now. The first test is slated for 2020.

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That move has raised concerns.

Daryl Kimball, executive director of the Arms Control Association, said the adaptation risks “crossing a long-standing line between U.S. missile defense being something that is only intended to help counter ‘rogue’ missile threats over to a program that Russia and China will see as being intended to counter significant portions of their strategic nuclear arsenals.”

The risk, Kimball said, is in how Moscow and Beijing respond.