Secretary of State Rex Tillerson, en route to Moscow days after a U.S. missile attack on Syria, is calling on Russia to realign itself with the West and break its alliance with Syrian President Bashar Assad.

His words came Tuesday as G-7 leaders in the Italian city of Lucca failed to reach a consensus on whether there should be new sanctions against Russia for its perceived role in last week's suspected Syrian chemical attack that prompted the U.S. strike. Scores of people were killed in the chemical attack on a rebel-held town in northwestern Syria.

"It is clear to us the reign of the Assad family is coming to an end," Tillerson said shortly before leaving for Moscow, according to Reuters.

"We hope that the Russian government concludes that they have aligned themselves with an unreliable partner in Bashar al-Assad."

At the G-7 meeting Monday night, British Foreign Secretary Boris Johnson said this was the moment for Russia to pick a side.

"I think it's very important that in these circumstances for the world to present a united front and for that there to be absolutely no ambiguity about the message and the message we are sending to the Russians is very, very clear: Do they want to stick with a toxic regime, do they want to be eternally associated with a guy who gases his own people or do they want to work with the Americans and the rest of the G-7 and indeed many other countries for a new future for Syria," Johnson told reporters.