Tension between Russia and the West over the civil war in Syria have escalated further, as U.S. Secretary of State Rex Tillerson flew to Moscow on the highest-level visit since President Donald Trump took office.
Before boarding a plane for Moscow following a meeting with Western allies in the Group of Seven (G7) in Italy, Tillerson urged Russia to abandon its support for Syrian President Bashar al-Assad after what he called a "barbaric" toxic-gas attack that killed dozens of civilians.
With Russian President Vladimir Putin giving no sign he intends to do that, the White House said Moscow was "isolated" and "getting on the wrong side of history."
"They have aligned themselves with North Korea, Syria, Iran," White House spokesman Sean Spicer told reporters in Washington. "That’s not exactly a group of countries you're looking to hang out with. With the exception of Russia, they are all failed states."
Speaking earlier in the Italian city of Lucca after G7 foreign ministers met with Middle Eastern allies to discuss the conflict in Syria, Tillerson said Russia must choose whether it will join the United States in seeking a peaceful future for Syria or continue to be aligned with Assad, Iran, and the Lebanese militant group Hizballah.
"Russia can be a part of that future and play an important role," Tillerson told reporters. "Or Russia can maintain its alliance with this group, which we believe is not going to serve Russia's interests longer term."
"We hope that the Russian government concludes that they have aligned themselves with an unreliable partner in Bashar Al-Assad," Tillerson added, calling last week"s alleged chemical attack on a rebel-held Syrian town an act of "barbarism."
Tillerson said it was unclear whether Russia had failed to take seriously its obligation to rid Syria of chemical weapons or if has merely been incompetent.
But he said the distinction "doesn't much matter to the dead."
"We cannot let this happen again," he said, referring to allegations that Assad ordered a nerve-gas attack last week on a rebel-held town. "We want to relieve the suffering of the Syrian people."
WATCH: Putin Claims Chemical 'Provocation' Planned In Syria
Putin Lashes Out
Tillerson later landed in Moscow, where he is to meet with Foreign Minister Sergei Lavrov on April 12. Putin's spokesman, Dmitry Peskov, said before Tillerson's arrival that a meeting with him was not on the president’s schedule "yet."
Russia has given Assad crucial diplomatic and military backing throughout the six-year-old war in Syria, which has killed more than 300,000 people and uprooted many more.
Moscow and Damascus have claimed that the toxic gas that killed dozens of civilians in the Idlib Province town on April 4 was released when government bombs struck a rebel-controlled chemical-weapons depot -- an assertion that Western governments reject and Tillerson has said was neither "plausible" nor "credible."
The United States on April 7 fired dozens of cruise missiles at a Syrian air base that Washington says was the launch site for the attack. That has drawn condemnation from Russia and Iran, another key Assad ally.
Lashing out at the West in his first public comments on Syria since the U.S. missiles strikes, Putin suggested the United States was looking for a pretext to push Assad from power.
Putin told a televised press conference just before Tillerson's arrival that Moscow will formally call for an international investigation into the Khan Sheikhoun incident.
He said Russia would appeal to UN agencies in The Hague to "thoroughly investigate" and make "balanced decisions based on the investigation's outcome."
He was apparently referring to the global chemical-weapons watchdog, the Organization for the Prohibition of Chemical Weapons (OPCW).
Putin also claimed Russia had received intelligence about planned "provocations" using chemical weapons that would put the blame on the Syrian government. He offered no evidence to back up the assertion.
"We have information from various sources that such provocations -- I cannot call them otherwise -- are being prepared in other regions of Syria, including in the southern outskirts of Damascus, where they are again planning to throw some kind of substance and accuse Syrian official authorities of using it," Putin said.
Putin also said the Western accusations against Assad reminded him of claims ahead of the U.S. invasion of Iraq in 2003 that Saddam Hussein had stockpiled chemical weapons.
Earlier, the Russian Foreign Ministry said Moscow was hoping to engage in "constructive cooperation" with Washington. "We hope that this is also what the American side wants," it added.
The ministry also announced that Lavrov would meet with the foreign ministers of Syria and Iran in Moscow later this week.
At the G7 talks on April 11, the ministers were divided on tougher measures to pressure Russia over its support of Assad.
Tillerson said after the meeting that the priority in Syria and Iraq remained the defeat of Islamic State extremists. But he said Moscow should realign with the United States and others toward that goal.
Britain and Canada have both said sanctions could be tightened against Russia if the Kremlin continues to support Assad’s government.
French Foreign Minister Jean-Marc Ayrault said the time has come for Russia to end the "hypocrisy" of its support for Assad.
"We say to the Russians," Ayrault said. "Grab this opportunity to distance yourselves from the horror of the regime of Bashar al-Assad and finally show with sincerity that you want peace."
Italian Foreign Minister Angelino Alfano said after chairing the G7 meeting that the ministers agreed there could be no military solution for Syria, and Russia must "insofar as possible" be involved in peace efforts.
"We do not believe that the military solution is the right one," Alfano said.
German Foreign Minister Sigmar Gabriel said Russia and Iran must both be involved in Syria's peace process. "Not everyone may like it, but without Moscow and without Tehran there will be no solution for Syria," he said.
Gabriel also said that Tillerson had focused on diplomatic initiatives during the April 11 talks in Lucca. "Tillerson explicitly said they are seeking a nonviolent, nonmilitary way," he said, praising Tillerson for taking "a very realistic and clear stance."
The need to engage with Russia also was echoed by Japanese Foreign Ministry spokesman Masato Ohtaka, who said Russia "can play a key role."
Also attending the G7 meeting on April 11 were the foreign ministers from five countries near Syria that oppose Assad’s rule -- Turkey, Saudi Arabia, the United Arab Emirates, Jordan, and Qatar.
Diplomatic pressure on Russia has been growing since April 4, when the alleged chemical air strike by Russian-backed Syrian forces killed more than 80 people in the rebel-held town of Khan Sheikhoun in Idlib Province.