WASHINGTON -- Just before departing Washington to travel to the NATO summit in Brussels, a meeting with Britain's prime minister in England, and an upcoming meeting with Russian leader Vladimir Putin in Helsinki, U.S. President Donald Trump made clear which one he was looking forward to more.

"Frankly, Putin may be the easiest of them all," Trump told reporters on July 10. "Who would think?"

While many Russia and national security experts in the United States are anticipating the July 16 Helsinki meeting with trepidation, arms control experts and close observers of the Trump White House said there was a reasonable chance that Putin and Trump could agree on new measures concerning their nuclear arsenals -- the world's two largest.

"The prospect of a private Trump-Putin meeting should give anyone paying attention great pause," Jon Wolfsthal, a top White House arms control and proliferation adviser under President Barack Obama, said in an op-ed published by the U.S. magazine Foreign Policy on June 10.

"But those risks must be weighed against the possible benefits of avoiding one of the greatest risks facing the United States today, that of nuclear conflict," he wrote.

Russian-U.S. relations have been battered in recent years, with confrontations and crises over the war in Syria, the conflict in eastern Ukraine and Crimea, U.S. accusations of Russian election meddling, and tit-for-tat expulsions of diplomats.

Arms control is no exception, and Exhibit A is the Intermediate-Range Nuclear Forces treaty, a landmark 1987 agreement that many experts consider a cornerstone of nuclear stability. The United States says Moscow has deployed a type of ground-launched cruise missile that violates the treaty, known as the INF.

Russia vehemently denies the allegation, although last year, after nearly four years of denials, it acknowledged the existence of the missile in question -- something called the 9M729 -- opening the door a tiny crack toward resolving the dispute.

In December, the Foreign Ministry published a statement on the agreement's 30th anniversary, saying it was prepared to discuss problems with the INF Treaty.

When arms control enters the Putin and Trump discussions, as Trump on July 12 confirmed it would at the conclusion of the NATO summit in Brussels, a review of New START would be the most likely place to start. The 2010 treaty, negotiated by Obama and a follow-up up to START I, agreed to in 1991, put sharp cuts on the number of nuclear warheads and so-called delivery vehicles.

In February, even with bilateral tensions spiraling, each country announced they had complied with the treaty's stipulation that they possess no more than 1,550 warheads. (See related graphic)

The treaty is set to expire in 2021, and each side has issued conflicting signals about whether they intend to seek a five-year extension, something the treaty allows for.

Trump himself has given mixed signals about New START and arms control more broadly.

During the 2016 election campaign, he repeatedly denounced New START, insisting without explanation that Moscow had deceived the United States in its compliance. Recently appointed national-security adviser John Bolton is a well-known critic of most arms-control treaties: shortly after the signing of New START, he argued that the accord's focus on Russian arms levels was "myopic" and could constrain U.S. nuclear flexibility. Some Republicans in Congress are deeply skeptical of New START.

U.S. Ambassador to Russia Jon Hunstman said that both New START and the INF Treaty would be up for discussion.

"I am guessing that this whole category of strategic stability, which is kind of a fancy bundling of various arms control features, will be prominent on the agenda," he told reporters on July 5.

The White House did not immediately respond to an e-mail seeking comment.

Putin has signaled he is open to extending the treaty. But complicating things is the fact that the two countries are upgrading their arsenals.

The Russian leader caught the world's attention in March with a speech and high-tech presentation that showcased advanced new weapons systems in development. That included an underwater drone and a low-flying, "unlimited range" cruise missile.

For his part, Trump has pledged to continue an ongoing modernization of the U.S. arsenal, whose size he's bragged about. And in the U.S. Nuclear Posture Review released the month before Putin's speech, Trump called for developing a nuclear-armed, sea-launched cruise missile, as well as a low-yield warhead for submarine-launched ballistic missiles.

Neither the new Russian nor U.S. weapons would fall under New START's limits. But even so, the weaponry -- along with new, broader guidance for when Washington would consider using its nuclear weapons -- added to fears of a new arms race. That, experts say, is something that neither country can afford.

"Without a positive decision to extend New START, and if the INF Treaty comes to an end, there would be no legally-binding limits on the world's two largest nuclear superpowers for the first time since 1972, and the risk of unconstrained U.S.-Russian nuclear competition would grow," Daryl Kimball, executive director of the Washington-based Arms Control Association, said in a statement.

Lynn Rusten, who served as a senior arms control adviser for the National Security Council between 2011-2014 and helped negotiate the 1991 START treaty, said "strategic stability" -- minimizing uncertainty that results in the potential use of either countries' arsenals -- was in each state's interest.

In other words, despite the bluster, neither side wants to use the weapons, and each side can benefit from knowing some of what the other side is doing with its declared weaponry.

"While I would love to see a concrete pronouncement come out on something like extension of New START, I think that's less likely," she said. "I think what's more likely is to begin a process and possibly set up a future summit early next year."

"It would be a glass three-quarters full if coming out of the meeting was an indication from both presidents that they recognize nuclear risk and those risks must be addressed, even when we have so many other differences and issues in our relationship," Rusten said.

The importance of New START, she said, isn't just about how broad a range of warheads and delivery systems -- intercontinental ballistic missiles, bombers, submarines -- it encompasses, but the verification system it sets up, reducing the potential of misunderstanding.

"We have Americans who literally go into Russia onto submarine bases and ICBM bases and bomber bases and get up close and personal to weapons systems, literally counting bumps on the top of a missile to ensure that the number of warheads declared is right. I mean, that's incredible," she said.

"If you lose that access over time, we'll have less and less understanding about what the Russians are doing in this area and that will lead to more and more worst-case planning and arms competition," she said.

Trump said in Brussels on July 12 that he planned to discuss with Putin both the possibility of extending New START and violations of the INF Treaty.

When asked, he also revealed what, in his opinion, the best result of his meeting with Putin would be.

"No more nuclear weapons anywhere in the world, no more wars, no more problems, no more conflicts," he told reporters. "That would be my ultimate."