The United States’ formal exit from a treaty banning intermediate- range, ground-based missiles is ushering in a new phase to the arms race that already is underway in Asia and the Pacific.

The end of the Intermediate- Range Nuclear Forces (INF) Treaty was announced in February and enacted Friday based on the U.S. contention that Russia was not abiding by it.

New Secretary of Defense Mark Esper, who stopped in Hawaii on Friday to meet with the head of U.S. Indo-Pacific Command on his way to Australia, said he would prefer the deployment of missiles with conventional explosives to Asia within months, but he acknowledged development work still is needed.

China said today it “will not stand idly by” if the U.S. deploys intermediate-range missiles in the Indo-Pacific region.

Russian President Vladimir Putin said Russia would deploy new intermediate- range missiles only if the United States does, and called for urgent arms control talks.

The Pacific Missile Range Facility on Kauai could play a key role, meanwhile, in the testing of multiple versions of the missiles — possibly as early as November — as well as with hypersonic missiles also being developed, defense experts said.

Intermediate-range ground-based cruise and ballistic missiles that travel between 310 and 3,417 miles are seen as particularly applicable across the vast reaches of the Pacific — and are needed to catch up with China and Russia, which have their own highly capable versions, defense officials say.

Esper told reporters that he met with Adm. Phil Davidson, head of Indo-Pacific Command in Hawaii, and asked him, “What do you see? What do you need as we try and compete? I mean, we’re in a compete phase right now with China when it comes to this theater. What assets do you need, what resources?”

Esper said Russia has been in noncompliance with the INF Treaty — which covered nuclear as well as conventional weapons — “for many, many years, going back to the Obama administration and maybe beyond that.” China was not a party to the treaty.

The U.S. “were the only ones in compliance of the INF Treaty,” Esper said, downplaying fears of a greater arms race. “I mean, Russia has been racing, if anybody, to develop these systems in violation of the treaty, not us,” he said.

Arms Control Association Executive Director Daryl Kimball said in a statement Friday that the loss of the treaty “is a blow to international peace.”

Russian noncompliance “is unacceptable and merits a strong response,” he said. But he added, “INF-class missiles, whether nuclear-armed or conventionally armed, are destabilizing because they can strike targets deep inside Russia and in Western Europe with little or no warning. Their short time-to-target capability increases the risk of miscalculation in a crisis.”

China, however, has built a formidable land-, sea- and air-based missile capability that is a major threat to U.S. interests in the South China Sea, defense experts say.

Raytheon and Lockheed Martin are competing to provide the Army with truck-mounted “Precision Strike” ballistic missiles that will have extended range and are expected to be transportable by C-17 cargo aircraft to islands or coastal countries in the Western Pacific.

White Sands Missile Range in New Mexico has been used for some missile testing, but the greater range planned means that facility can’t be used.

“We have a plan to address increasing range,” Army Col. John Rafferty said last month at a Center for Strategic and International Studies forum. “The White Sands Missile Range is a great facility that’s accommodating just about everything but can’t quite get 499 (kilometers) or beyond, so we’re going to find areas in the Pacific to do this.”

Thomas Karako, who is with the strategic studies group, said PMRF is one option for testing. But Kwajalein Atoll and an Australian range are other possibilities.

Guam and Diego Garcia in the Indian Ocean could serve as bases for intermediate-range ground-based missiles, he said. Another option is coastal countries and island nations that could choose to host the missiles.

“We have some very good friends and allies that include — but is not limited to — Japan, South Korea, the Philippines and some other folks,” Karako said. “Some of these countries have lots and lots of islands.”

Karako said it’s premature to predict where missiles might be based.

“We have to let the process develop, and we have to give diplomacy a chance to figure out what makes sense for the future fielding of these things,” he said.

The Army, Navy and Air Force are also developing hypersonic weapons that attain speeds of more than Mach 5, or five times the speed of sound — at least 3,800 mph.

In a 2011 test a hypersonic vehicle was launched from PMRF and arrived 30 minutes later at the Reagan Test Site at Kwajalein, Marshall Islands — a distance of about 2,500 miles, the Army said. A submarine-launched hypersonic missile was tested at PMRF in 2017, meanwhile.

Like the new intermediate-range missile capability, operational hypersonic missiles are expected to be available in a few years.

Based at Barking Sands, the missile facility extends over vast ocean areas west of the island and is the world’s largest “instrumented range,” according to the Navy. It incorporates more than 1,100 square miles of instruments underwater and 42,000 square miles of controlled airspace and can support surface, subsurface, air and space operations at the same time.

PMRF is a “very logical place” for continued testing “because the telemetry is the best in the world,” said Riki Ellison, chairman of the nonprofit Missile Defense Advocacy Alliance.

“It’s the Navy’s test yard with all the submarines and its warfare and those exercises it does. It’s one of the most sought-after test ranges,” Ellison said.

The Associated Press contributed to this report.