Are We Headed for Another Expensive Nuclear Arms Race? Could Be.

BRUSSELS — After the recent death of the treaty covering intermediate-range missiles, a new arms race appears to be taking shape, drawing in more players, more money and more weapons at a time of increased global instability and anxiety about nuclear proliferation.

The arms control architecture of the Cold War, involving tens of thousands of nuclear weapons, was laboriously designed over years of hard-fought negotiations between two superpowers — the United States and the Soviet Union. The elaborate treaties helped keep the world from nuclear annihilation.

Today, those treaties are being abandoned by the United States and Russia just as new strategic competitors not covered by the Cold War accords — like China, North Korea and Iran — are asserting themselves as regional powers and challenging American hegemony.

The dismantling of “arms control,” a Cold War mantra, is now heightening the risks of a new era when nuclear powers like India and Pakistan are clashing over Kashmir, and when nuclear Israel feels threatened by Iran, North Korea is testing new missiles, and other countries like Saudi Arabia are thought to have access to nuclear weapons or to be capable of building them.

The consequence, experts say, is likely to be a more dangerous and unstable environment, even in the near term, that could precipitate unwanted conflicts and demand vast new military spending among the world’s biggest powers, including the United States.

“If there’s not nuclear disarmament, there will be proliferation,” said Joseph Cirincione, a nuclear analyst and president of the Ploughshares Fund, a global security foundation. “If big powers race to build up their arsenals, smaller powers will follow.”

“As long as the big boys cling to their toys, others will want them,” he added, quoting the former head of the International Atomic Energy Agency, Mohamed ElBaradei.

Not only are the big boys clinging to them, there are more big boys now, and they want more toys.

For Washington, China is seen as a rising strategic rival and competitor. And the United States is moving to increase its military presence and missile deployments in Asia, as a deterrent against a more aggressive Beijing, which has vastly expanded and modernized its stock of medium-range missiles that can hit American ships, as well as Taiwan.

At the same time, President Trump’s national security adviser, John R. Bolton, has talked about letting the last strategic-arms control treaty, New START, die in February 2021, without extending it another five years, as foreseen in the accord, which was signed under President Barack Obama.

With no limits on nuclear weapons, and no system of on-site verification or information exchange, a very expensive new arms race seems almost inevitable with Moscow — and would probably accelerate another with Beijing.

Free of the Intermediate-Range Nuclear Forces Treaty, the Trump administration is testing, and wants to deploy, a new generation of land-based intermediate-range missiles in Asia. As it does, Mr. Trump’s stated desire to pull China into three-way arms talks seems further away than ever.

“Something bad is happening, and we’re on the verge of an environment where there are no limits or verification between us and Russia,” said Lynn Rusten, who was an arms-control official in the Obama administration. “We’re losing one of the key guardrails that moved the U.S. and Russia away from nuclear confrontation. At least during the Cold War we were talking to one another.”

Richard J. Burt helped negotiate the I.N.F. treaty and directed the negotiations that led to a more sweeping Strategic Arms Reduction Treaty, known as START I, under President George Bush. Without New START, he said, “there will no longer be any on-site inspections or transparency, so you’re back to assuming the worst of what your adversary is doing.”

“In the 1970s and ’80s, even decision makers will say the U.S. and Soviet buildup was insane — both sides overbuilt without predictability, and that’s where we’re headed,” Mr. Burt said. In the 1960s, ’70s and ’80s, United States military spending was roughly 7 percent of economic output, compared with just over 4 percent now.

Add China to the mix, Mr. Burt said, and “we could be spending huge amounts of money soon.”

“We’re talking of modernizing the whole U.S. triad, with new ICBMs, subs and bombers,” he said. “That will be in excess of a trillion dollars, and doesn’t include medium-range or hypersonic missiles.”

Radoslaw Sikorski, a former Polish defense minister and now a European legislator, said simply: “We have dismantled virtually all the arms-control architecture of the Cold War, and that’s not a good thing. And we have an administration in Washington that overestimates American power.”

Even after decades of reducing arsenals, the United States and Russia still possess more than 90 percent of the world’s nuclear weapons — more than 8,000 warheads, enough to destroy the world several times over. New START limited the number of deployed nuclear warheads on each side to around 1,550, a cut of about two-thirds from START I.

But when President Vladimir V. Putin of Russia spoke to Mr. Trump about renewing New START in their first telephone conversation in February 2017, Mr. Trump attacked the treaty, claiming that it favored Russia and was “one of several bad deals negotiated by the Obama administration.”

In June, Mr. Bolton — who has made no secret of his view that international pacts are unenforceable and constrain the United States — said that New START was unlikely to be extended, in part because it does not cover tactical nuclear weapons.

But in nuclear matters, the perfect can be the enemy of the good, said Jon Wolfsthal, who was a senior director for arms control on Mr. Obama’s National Security Council.

Mr. Trump’s desire to engage China is a good one, Mr. Wolfsthal said.

“There’s lots of areas of concern to talk about,” he said, listing China’s military and naval buildup, its anti-ship missiles, and Chinese concerns like American missile deployments, missile defense, cyberwarfare and space.

“But the idea that China will jump into bed with the U.S. and Russia on arms control and lock in their inferior status is crazy,” Mr. Wolfsthal said, especially at a time when Washington is pushing a trade war with Beijing and selling arms to Taiwan.

Just last week, Defense Secretary Mark Esper said that with the I.N.F. treaty now dead, he would like to begin deploying American land-based intermediate-range missiles in Asia “sooner rather than later,” even “within months.”

China responded immediately, warning that any such deployment would “clearly be extremely offensive in nature.” Fu Cong, China’s top arms-control official, said Beijing “would take countermeasures” and emphasized that China had “no interest” in Mr. Trump’s call for three-way arms control talks.

Thomas M. Countryman, former assistant secretary of state for international security and nonproliferation, said that China, with a small nuclear arsenal of about 300 warheads and a different strategic theory, had little incentive to join such talks.

China practices “minimal deterrence” and vows “no first use” of nuclear weapons. Its arsenal is small enough not to represent a first-strike threat to either Washington or Moscow, but large enough — and hidden enough — to have a credible retaliatory capability.

Whereas arms control treaties between Washington and Moscow depended on inspections and transparency, “China sees those as eroding the few advantages they have,” Mr. Countryman said.

While the American military “may have lots of reasons to see China’s growing conventional strength as an offensive threat to U.S. assets and allies,” he said, “you can’t say the same thing about China’s nuclear arsenal.”

But if New START ends, the nuclear arsenals of both Moscow and Washington will be so large and so unknowable that “it’s almost an invitation for China to build up its arsenal,” said Mark Fitzpatrick, an arms control expert with the International Institute for Strategic Studies.

China feels vulnerable because of the sophistication of even conventional American missiles, bombers and strategic missile defenses, which could threaten China’s retaliatory capability, he said.

The effects of abandoning arms control may not be apparent for years, since developing new weapons and policies takes time. “But when you break the crockery, something is broken,” Mr. Fitzpatrick said.

And no one ever admits to starting an arms race, Mr. Countryman said. “It’s always a response to what the other guys have done.”

China is building up its military rapidly, as is Russia — moves that in their eyes keep them competitive with the United States, which spends far more. But so are other regional powers, as they take advantage of American opposition to multilateral agreements and Mr. Trump’s desire to reduce the country’s responsibilities and footprint abroad, as in Syria and Afghanistan.

Mr. Burt proposes extending New START and then negotiating a further reduction with Moscow to 1,000 deployable warheads each, “and then you can possibly bring in the Chinese to accept a limit on their existing stockpile — that is at least worth trying.”

Otherwise, he said, “we’re heading for a much more expensive arms race.”

And the failure of the big boys to reduce their nuclear toys will only prompt others to make them.