Secretary of State Rex Tillerson declared that U.S.-Russia relations have hit a “low point” marked by serious mistrust and differences over international issues, including the conflict in Syria.

Tillerson spoke at a news conference in Moscow after what he said was a “very frank” two-hour meeting with Russian President Vladimir Putin.

“I expressed the view the current state of U.S.-Russia relations is at a low point,” said Tillerson, who spoke alongside Russian Foreign Minister Sergey Lavrov. “There is a low level of trust between our two countries.”

The top U.S. diplomat said that both sides understand that “improvement in the long-term relationship is required” to resolve the conflicts in Syria and Ukraine.

Tensions between Moscow and Washington have flared in the aftermath of a chemical attack in Syria that the U.S. and other world powers say was carried out by Syrian President Bashar Assad, who is backed by Russia.

President Trump responded to that attack by launching 59 cruise missiles at the Syrian air base, angering Russian officials who have denied that Assad used chemical weapons.

Even amid their fierce disagreement over Syria, both diplomats said they would cooperate in an international investigation into the gas attack.

“We want there to be a frank investigation," Lavrov said.

But on the substance, the strained relationship was on full display during Wednesday’s news conference. Tillerson said the U.S. remains “quite confident” in its assessment that the Syrian government was behind the April 4 chemical attack.

He also stressed the Trump administration’s belief that Assad’s rule “is coming to an end.”

"The characterization is one Assad has brought upon himself," Tillerson told a reporter who asked about White House press secretary Sean Spicer’s incorrect statement that even the Nazis hadn't used chemical weapons on their own people.

Lavrov again did not say whether Assad was behind the attack, even as he said a United Nations investigation was necessary.

He also said it’s not Russia’s goal to help remove Assad from power. The Syrian leader is Moscow’s closest ally in the Middle East.

"Removing or ousting a particular personality from this scene is not in our objective,” he said.