MOSCOW (Reuters) - Russia and the United States agreed to set up a working group to try to mend their battered ties on Wednesday after U.S. Secretary of State Rex Tillerson held lengthy talks in Moscow with President Vladimir Putin and the Russian foreign minister.

Russian Foreign Minister Sergei Lavrov shakes hands with U.S. Secretary of State Rex Tillerson during a news conference following their talks in Moscow, Russia, April 12, 2017. REUTERS/Sergei Karpukhin

It was not clear until the last minute whether Putin would grant Tillerson an audience, but the fact that he did is likely to be seen as a sign that Moscow has not given up on the new U.S. administration and wants to try to improve ties which both sides agree are languishing at a post Cold War low.

A joint news conference between Sergei Lavrov, the Russian foreign minister, and Tillerson showed how much work there is to do though as the Russian used many of his speaking opportunities to lambast Washington over its actions in Syria and what he said was its unhelpful foreign interference in the past.

Tillerson, on his first visit to Russia in his current role, struck a more conciliatory stance, but said ties and trust levels were at a low point and restated Washington’s position that Syrian President Bashar al-Assad must eventually relinquish power, a position starkly at odds with Russia.

“There is a low level of trust between our two countries,” Tillerson said. “The world’s two foremost nuclear powers cannot have this kind of relationship.”

Lavrov said that while Russia was not placing its hopes in Assad or any other individual in Syria, toppling the Syrian government was not an option and that a political process had to be allowed to play out.

“We discussed Assad today,” said Lavrov. “I don’t remember any positive examples of how a dictator was overthrown and everything was just fine afterwards.”

Differences over a U.S. missile strike on a Syrian air base last week also bubbled to the surface.

Washington says it acted to punish the Syrian government for what it said was a devastating nerve gas attack Damascus launched against its own people that killed scores.

Russia said the U.S. strike was illegal though and Lavrov repeated Moscow’s stance on Wednesday, saying an international investigation should be left to determine who was to blame and what happened.

It was wrong to blame Assad without knowing the facts, he said.

Tillerson said the United States was confident that Assad’s forces were behind the gas attack, but said there was “no firm information” to indicate Russian forces were involved in the same attack.

In a move that slightly softened the atmosphere, Lavrov said Putin had agreed to restore a U.S.-Russia air safety agreement covering Syria which Moscow suspended in retaliation for the U.S. missile strikes.

The agreement would be reactivated with immediate effect, Viktor Ozerov, the head of the Russian upper house of parliament’s defense committee told the RIA news agency.