President Trump delivers a speech at the Great Hall of the People in Beijing on Nov. 9, 2017. (Damir Sagolj/Reuters)

When President Trump announced Saturday that the United States would be pulling out of a landmark nuclear-arms agreement with Russia, he blamed Moscow for the decision.

“Russia has violated the agreement. They’ve been violating it for many years,” Trump told reporters in Nevada, referring to the Intermediate-Range Nuclear Forces (INF) Treaty. “I don’t know why President Obama didn’t negotiate or pull out.”

But Trump also hinted that another country played a role, one that it isn’t even party to the treaty: China.

“Unless Russia comes to us and China comes to us and they all come to us and say, ‘Let’s really get smart and let’s none of us develop those weapons,’” Trump said. “But if Russia’s doing it and if China’s doing it and we’re adhering to the agreement, that’s unacceptable.”

Why does China play into Trump’s decision-making on the treaty? And what effect does he think pulling out of the agreement might have on relations with Beijing? Here’s a guide.

What is the INF Treaty?

The treaty bars the United States and Russia, along with a number of post-Soviet states, from possessing, producing or test-flying ground-launched nuclear cruise missiles with a ranges of 500 to 5,500 kilometers (300 to 3,400 miles).

The agreement was signed in 1987 by President Ronald Reagan and Soviet leader Mikhail Gorbachev and took effect the following year after it was ratified by the U.S. Senate. It came after years of negotiations, sparked by the installation of weapons systems that put Western Europe within easy reach of a Soviet missile strike.

In many ways, the treaty was a real success. It was the first agreement to actually reduce nuclear missile stockpiles. By 1991, nearly 2,700 U.S. and Soviet missiles were eliminated. The pact is the only Cold War arms-control agreement that remains in force.

In recent years, however, there has been talk of violations by both sides. The United States is particularly concerned by a ground-launched cruise missile known as the SSC-8, while Russia says that missile-defense installations in Europe violate the treaty.

How does China factor in to deliberations?

China has never been a party to the INF Treaty. As such, it hasn’t had the same limitations placed upon its stockpiles of short- and intermediate-range missiles for the past three decades.

During Senate testimony last year before he retired as head of the U.S. Pacific Command and became the U.S. ambassador to South Korea, Adm. Harry Harris said the Chinese People’s Liberation Army now has the “largest and most diverse missile force in the world, with an inventory of more than 2,000 ballistic and cruise missiles.” He added that 95 percent of those missiles would violate the INF Treaty if China were a signatory.

Many national security officials believe the missiles threaten U.S. military interests in the region. Earlier this year, Eric Sayers, a special assistant to Harris, wrote that “in the coming decade the growing conventional military imbalance could well mean that the United States will not be able to uphold its security commitments to allies or reassure partners in the Indo-Pacific in the face of an increasingly assertive China.”

For the Trump administration, pressuring China is key part of its foreign policy. At the start of the year, Defense Secretary Jim Mattis unveiled a new Pentagon strategy that identified China and Russia as key threats to the United States and called for sustained financial investment in the military to overcome “a period of strategic atrophy.”

Meanwhile, Trump’s aggressive trade policy against China has widely been interpreted as a broader attempt to control and contain a rising China before it is too late.

National security adviser John Bolton, believed to be a driving force behind Trump’s move, has suggested that China may even be a more important factor than Russia. He has told U.S. allies that the INF Treaty puts the United States in an “excessively weak position” against Russia “and more importantly China,” one diplomat told The Washington Post.

Could the United States get China to agree to INF-style restrictions?

It’s not clear what exactly the United States is hoping to achieve, but there may be hopes for a new treaty that would include China. Such an idea may even get support from Moscow, which has voiced concerns about Chinese missiles in the past.

Sen. Rand Paul (R-Ky.), a critic of Trump’s INF decision, mooted the idea during an interview with Fox News on Sunday. “I’m all for trying to sign an agreement with China, but that would have to be a brand-new agreement. It’s no reason to end the agreement we have with Russia,” he said.

But many analysts believe it’s unlikely that China would be interested in joining either the INF or another treaty. “Given the size of China’s conventional ballistic arsenal, this would be require some very creative diplomacy!” wrote M. Taylor Fravel, an associate professor of political science at MIT, on Twitter.

China also may hesitate to join an arms-control treaty with the United States, given that Washington is unilaterally pulling out of another such agreement. On Monday, Chinese Foreign Ministry spokeswoman Hua Chunying said that “the U.S. unilateral withdrawal from the treaty will have a multilateral negative effect.”

Could the United States try to match China in the region?

Experts such as Sayers have suggested that installing the ground-based missile systems banned by the INF Treaty could open China’s interior to U.S. attacks, increasing China’s need for costly defense systems.

Congress’s annual defense authorization bill has funded research and development into weapons that could potentially violate the INF Treaty, specifically making the argument that these weapons could be used to counter China if the agreement were scrapped.

A big question, however, is how useful such missiles would actually be in a standoff with China. The INF Treaty banned ground-launched missiles, but the United States does not have easy access to that much land around China. Missiles could certainly be placed in Guam, a U.S. island territory in the Pacific, but placing them in countries such as Japan or the Philippines would require more complicated negotiations.

“I don’t see U.S. allies in Asia rushing to host U.S. road-mobile INF-range weapons,” said Kingston Reif, director of disarmament and threat-reduction policy at the Arms Control Association. “We could put them in Guam, but China no doubt has every inch of the island targeted.”

The vice chairman of the Joint Chiefs of Staff suggested during a Senate hearing last year that sea- and air-based missiles in the region are already capable of dealing with the threat from China, which raises questions about the value of implementing new systems banned by the INF.

Read more:

Why China is so mad about THAAD, a missile defense system aimed at deterring North Korea

What made North Korea’s weapons programs so much scarier in 2017

What the INF Treaty means for the U.S. and Europe — and why Trump mentioned China