Presidents Joe Biden and Vladimir Putin of Russia spent more than three hours discussing issues Wednesday at their summit in Geneva. They ticked through their respective lists so quickly and in such “excruciating detail,” Biden says, that they looked at each other and thought, “OK, what next?”

The most pressing issues the leaders discussed:

Ambassadors

Biden and Putin agreed to return their respective ambassadors to Washington and Moscow in a bid to improve badly deteriorated diplomatic relations between their countries.

Russia’s ambassador to the United States, Anatoly Antonov, left Washington in March amid a row after Biden called Putin a killer in a television interview and imposed new sanctions on Russia over its treatment of opposition figure Alexei Navalny.

John Sullivan, the U.S. ambassador to Russia, flew out of Moscow in April after public suggestions from Russian officials that he should leave to mirror Antonov’s departure.

Both ambassadors were present at Wednesday’s summit.

Putin also said the Russian foreign ministry and the U.S. State Department would begin consultations on other vexing diplomatic issues, including the closures of consulates in both countries and the employment status of Russian citizens working for U.S. missions in Russia.

A senior Biden administration official said Sullivan is likely to return to Moscow next week. A different senior administration official said both governments had begun discussing consulate and local staff issues and the hope was an agreement could be reached in the next two months.

Neither administration official was authorized to comment publicly by name and both spoke on condition of anonymity.

Cybersecurity

No breakthroughs on this issue were announced, but the leaders agreed to at least talk about what has become a major source of conflict between the U.S. and Russia.

Biden said he and Putin agreed to have their experts work out an understanding about what types of critical infrastructure would be off-limits to cyberattacks. He said the U.S. presented Russia with 16 specific types of infrastructure, including energy, elections, banking and water systems, and the defense industry.

The agreement comes amid a flood of ransomware attacks against U.S. businesses and government agencies, including one in May that disrupted fuel supplies along the East Coast for nearly a week. The disruption was blamed on a criminal gang operating out of Russia, which does not extradite suspects to the U.S.

Other serious incidents include the SolarWinds intrusion discovered last year in which hackers, believed by U.S. authorities to be Russian, penetrated multiple U.S. government networks and prompted Biden to impose additional U.S. sanctions against Russia.

Biden said the U.S. and Russian governments would follow up on certain criminal cases, an apparent reference to cybercriminals operating with impunity from Russian territory.

Putin agreed there is mutual interest in the subject.

Biden also made an implicit threat against Russia, saying the U.S. has “significant cyber capability” it could use against Russia if it were to interfere with U.S. critical infrastructure.

Nuclear Weapons

Biden and Putin instructed their diplomats to begin laying the groundwork for a new phase of arms control.

The “strategic stability dialogue” would be a series of discussions designed to set the table for a negotiation by sorting out what exactly should be negotiated. More broadly, it would aim to reduce the risk of war between the world’s two largest nuclear powers.

Biden said the goal is to work with Russia on “a mechanism that can lead to control of new and dangerous and sophisticated weapons that are coming on the scene now, that reduce the time for response, that raise the prospect of accidental war.” He said this was discussed in detail.

No date was announced for the start of talks.

The basic idea is to identify and sort out the many areas of disagreement over what a future arms control treaty should address. It also would address ways to avoid unintended or accidental moves that could trigger war.

Shortly after Biden took office in January, he and Putin agreed to extend until 2026 the New START treaty that limits long-range nuclear weapons. The challenge now is to work out what a potential follow-on pact would include.

The Russians insist it include defensive weapons, such as U.S. missile defense systems. The Americans argue that it should include so-called tactical nuclear weapons, which are not covered by New START and of which the Russians have a far larger number deployed. It might also include new and emerging technologies such as hypersonic missiles and space weaponry.

Prisoner Exchange

Biden said he raised with Putin the plight of two Americans detained in Russia.

Putin had opened the door to possible discussions about a prisoner swap with the U.S. and said those conversations would continue. Biden said he would follow up, too.

The U.S. is holding two prisoners whose release Russia has sought for more than a decade, including arms trader Viktor Bout. The other is Konstantin Yaroshenko, a pilot who was extradited from Liberia in 2010 and convicted the next year of conspiracy to smuggle cocaine into the U.S.

Biden said Americans Paul Whelan and Trevor Reed are being “wrongfully imprisoned” in Russia.

Whelan, who also holds Canadian, Irish and British citizenship, was arrested in Moscow in 2018, convicted of espionage and sentenced to 16 years. Whelan says he was just visiting Moscow.

Reed was convicted of assaulting a police officer while intoxicated and sentenced to nine years. Putin, in a recent interview with NBC News, called Reed a “drunk and a troublemaker.”

Human Rights

Biden said he’ll continue to air with Putin concerns about basic human rights because it is a core tenet of what the United States stands for.

Biden said he couldn’t be president of the United States and not raise human rights issues during the summit with Putin. He mentioned the internationally publicized case of jailed Russian opposition leader Alexei Navalny.

But Putin said Navalny got what he deserved when he was handed a stiff prison sentence. Navalny is Putin’s most ardent political foe. He was arrested in January after returning to Russia from Germany, where he’d spent five months recovering from nerve agent poisoning that he blames on the Kremlin. Russian officials deny involvement in Nalvany’s poisoning.

Navalny received a 30-month prison sentence for violating terms of a suspended sentence from a 2014 embezzlement conviction he dismissed a politically motivated.

Syria

Biden pressed Putin to drop a push to close the last international humanitarian crossing into Syria, making clear the matter was of “significant importance” to the U.S.

No deal was reached to keep it open, however.

Russia is threatening to use its U.N. Security Council veto to close the aid route for millions of Syrians internally displaced by that country’s war.

Afghanistan and Iran

Biden said Putin asked about Afghanistan and expressed a desire that peace and security be maintained there. Biden said he told Putin that a lot of that will depend on him, and that Putin indicated he was prepared to “help” on Afghanistan as well as on Iran.

Biden declined to go into further detail. Biden’s administration is mounting new efforts to get Iran to comply with the terms of a nuclear deal it had once agreed to before Biden’s predecessor, Donald Trump, withdrew the U.S. from the agreement the U.S. and other world powers struck with Iran in 2015.

Putin also talked about preventing a resurgence of terrorist violence in Afghanistan. Biden said it would be very much in Russia’s interest to not see that happen.