The Trump administration is “very, very early in the process of considering” what it wants to do about the main existing arms control treaty between the United States and Russia, White House national security adviser John Bolton said Thursday after meeting with his Russian counterpart.

The New Start agreement, limiting both sides’ strategic nuclear arsenals, expires in early 2021. When he met with President Trump in Helsinki last month, Russian President Vladi­mir Putin said he was ready to implement a five-year extension built into the treaty.

Putin and Trump have spoken extensively about modernizing their separate nuclear arsenals, but the Trump administration has not indicated a position on the treaty limits.

After a five-hour meeting in Geneva with Putin adviser Nikolai Patrushev, Bolton said that U.S. options include extending the 2010 New Start accord negotiated by President Barack Obama, renegotiating it or returning to the agreement it replaced — the one-page Moscow Treaty signed in 2002 by President George W. Bush.

“That’s a possibility,” Bolton said of the Moscow Treaty. “All of these are things the United States is going to consider, along with what to do about the INF,” a separate accord on intermediate-range nuclear weapons that the two sides have accused each other of violating.

The Bolton-Patrushev meeting was the only substantial agreement to come out of the presidential talks in Helsinki. While Bolton said they made “a lot of progress” in discussing “how to restore in certain respects diplomatic and other exchanges and ways in which we could cooperate and expand our common efforts,” he did not provide details.

Patrushev, in separate comments to the news media, said progress was made “in certain areas where lines of communications could be restored, and more work done by agencies — State, Defense and others,” according to the Russian news agency Tass. “Contacts between the foreign ministries will resume, as well,” he said.

Both said they had failed at an attempt to write a joint public statement about their talks. “I felt it was important to mention election meddling, which we raised a number of times,” Bolton said, but Patrushev disagreed.

“I made clear that we wouldn’t tolerate meddling in 2018, and that we were prepared to take necessary steps to prevent it from happening,” Bolton said.

Patrushev, according to state-run RIA news agency, said that no statement had been written “because the Americans wanted this to say that we had meddled in their elections, as is their opinion, but we deny this.”

Bolton said they also discussed Syria and Iran.

The administration has demanded that Iran, a Russian ally in support of Syrian President Bashar al-Assad, withdraw all of its “regular and irregular” military forces from Syria. “That would be an objective that I think President Putin would share,” Bolton said without elaboration. But “it’s far from easy to achieve. We talked about a variety of ways it might be accomplished through a series of steps.”

Bolton said that he rejected, as Secretary of State Mike Pompeo had in earlier discussions, a Russian proposal to geographically “constrict” Iranian forces to a certain part of Syria — away from Israel’s border — in exchange for U.S. suspension of sanctions it plans to impose on Iranian oil exports in November.

Bolton said he explained that the administration’s intention was “to put maximum pressure on the [Iranian] regime and to tighten up the sanctions so that they would be at a minimum equal to the sanctions in effect” before the 2015 Iran nuclear agreement, from which Trump withdrew the United States in May.

Extending New Start, which Bolton denounced at its inception as undermining U.S. national security interests, has long been a Russian priority. When Putin brought it up during his first telephone call with the new U.S. president in February 2017, Trump reportedly was unsure what the treaty was and called it another “bad deal” negotiated by Obama. The White House later denied Trump was unaware of the terms of the treaty.

Daryl Kimball, executive director of the Washington-based Arms Control Association, said that reactivating the terms of the Moscow Treaty — which contained no monitoring or verification provisions for caps on numbers of deployed strategic weapons — would be a poor substitute for New Start.

“Without a positive decision by the two presidents to extend the treaty by five years . . . there would be no legally binding limits on the world’s two largest arsenals for the first time since 1972,” he said. Some arms control experts have countered that there is no reason to act now to extend the treaty — a move that requires only presidential approval — and have argued that it is better to wait to see how U.S.-Russian relations evolve.

Bolton was asked whether Trump’s difficult week in Washington, including the felony convictions of former campaign chairman Paul Manafort and Michael Cohen, Trump’s former personal lawyer, made him “concerned that your own president is a security risk.”

“Of course not,” Bolton said. “I mean, that’s a silly question. . . . Have a little faith in the American people, who elected him president.”

Amie Ferris-Rotman in Moscow contributed to this report.