Only about 62 percent of Asia-Pacific command requests for attack submarines are fulfilled because of shortfalls and as China “continues its pattern of destabilizing militarization of the South China Sea,” the head of U.S. Pacific Command testified Tuesday.

“We have a shortage in submarines,” Adm. Harry B. Harris Jr. told the U.S. Senate Armed Services Committee. “My submarine requirement is not met in PACOM, and I’m just one of many (combatant commanders) that will tell you that. But that’s our principal asymmetric advantage over China and any other adversary, and I think we have to keep after it.”

Harris, headquartered at Camp H.M. Smith, said the strategic re-balance “has taken hold,” but there’s more work to do “and we must not lose the momentum.” He said he needs weapon systems “of increased lethality that go faster, go further and are more survivable.”

Harris and Gen. Curtis Scaparrotti, head of U.S. Forces Korea, testified on future years’ defense. China’s placement of an HQ-9 surface-to-air missile battery and advanced radar on contested islands in the South China Sea was front and center.

“China’s increasingly assertive pattern of behavior calls into serious question whether China’s rise will in fact be peaceful,” said committee Chairman U.S. Sen. John McCain, R-Ariz. “Despite U.S. efforts to re-balance to the Asia-Pacific, U.S. policy has failed to adapt to the scale and velocity of the challenge we face.”

McCain called for “robust” freedom of navigation demonstrations, additional exercises and exploration of sanctions against Chinese companies involved in the island-building land reclamation “that has destabilized the South China Sea.”

Harris said China is “clearly militarizing the South China Sea, and you have to believe in a flat Earth to think otherwise.” He added that China’s placement of missiles and radars, runway construction and other actions are changing the operational landscape there.

China’s DF-21 and DF-26 anti-ship ballistic missiles “could pose a threat to our (aircraft) carriers,” Harris said. “I think, though, that our carriers are resilient, and we have the capability to do what has to be done if it comes to that.”

Harris said that when he started flying P-3 Orion sub-hunters in the 1970s, “we had the Harpoon missile — and that’s the same missile that we have today.” But there is more funding in fiscal 2017 to increase the lethality of surface-to-surface missiles, he said.

Harris also mentioned the SM-6 missile and long-range anti-ship missile, which is “another great capability that we need to bring online fast.”

The Pacific commander said the submarine shortfall is “solely because of numbers.” Two new Virginia-class attack subs are being built each year to replace older Los Angeles-class vessels that are being retired at a faster rate. Pearl Harbor has four Virginia subs.

Harris was asked about the threat to U.S. aircraft carriers from Chinese long-range missiles as part of China’s “anti-access, area denial,” or A2/AD, strategy.

Harris responded, “I think, again, the original stealth platform is the submarine, and we’ll be able to win in any conflict at sea when we apply the joint force to that. I’m comfortable with the carrier operating in those waters. … We have to consider the threat. But the Chinese A2/AD threat is not 10 feet tall. It’s not even 6 feet tall, in my opinion.”