U.S. Submarines Will Be First Ships to Get New Hypersonic Missiles, O'Brien Says

National Security Adviser Robert O'Brien has said that American submarines will be the first Navy vessels to get hypersonic missiles, followed by the U.S. destroyer fleet.

O'Brien spoke at the Portsmouth Naval Shipyard in Maine on Wednesday, laying out plans for the modernization and expansion of the U.S. Navy to face new threats including China, Defense News reported.

The Navy and Army are cooperating on a hypersonic missile—the Common-Hypersonic Glide Body, or C-HGB—which underwent its first successful test launch in March. O'Brien said that when operational, hypersonic weapons would first be put on the most advanced class of American submarines.

"The Navy's Conventional Prompt Strike program will provide hypersonic missile capability to hold targets at risk from longer ranges," O'Brien said. "This capability will be deployed first on our newer Virginia-class submarines and the Zumwalt-class destroyers. Eventually, all three flights of the Arleigh Burke-class destroyers will field this capability."

The U.S. is still lagging behind Russia and China on hypersonic weapons. Both Moscow and Beijing have operational hypersonic missiles, whose high speed—Mach 5 and above, or around 3,836 miles per hour—relatively flat trajectory, and in-flight maneuverability makes them difficult for existing defenses to stop.

President Donald Trump has lauded America's hypersonic research as part of his boasts of American military strength, though he incorrectly named the weapons. He told a rally in Arizona Monday: "We have hydrosonic missiles that go seven times faster than a normal missile...We have the best hydrosonic in the world."

Military officials see hypersonic technology as vital to maintaining America's edge against Russia and China. In Asia particularly, the U.S. is keen to fit its vessels with hypersonic missiles. The South China Sea and Taiwan Strait are key flashpoints, where American and Chinese warships and aircraft have tense encounters over Beijing's territorial claims.

Hypersonic missiles are part of a wider strategy to expand the size of the U.S. Navy and put less emphasis on large, manned vessels like aircraft carriers, to smaller, faster, heavily-armed vessels, some of which will eventually be unmanned.

O'Brien is pushing for a 500-ship Navy by 2045, up from the current target of 355 manned ships by 2030. This so-called "Battleforce 2045" project was first announced by Secretary of Defense Mark Esper.

Former acting Navy secretary Thomas Modly told Forbes Wednesday he remains skeptical about the Battleforce 2045 proposal. Modly said that Esper and O'Brien came up with the idea "but no one from the Navy to include myself, the CNO, the Commandant, or any senior three-star involved in developing the shipbuilding plans budget were invited."

"Math is a very stubborn thing," Modly said. "If you are going to increase the size of the fleet from 275 to 355, or 500, and you aren't going to increase the Navy's top line to pay for it, you've merely created a mathematical challenge for yourself that cannot be solved."

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The Virginia-class submarine USS Vermont transits the Thames River while conducting routine operations in Groton, Connecticut, on October 15, 2020. Petty Officer 3rd Class Christian Bianchi/U.S. Navy