US Secretary of State Rex Tillerson on Tuesday said Russia can either join the US, or side with Syrian President Bashar al-Assad, his Iranian allies, and Hezbollah.

"Russia has really aligned itself with the Assad regime, the Iranians and Hezbollah," Tillerson said at a meeting of G-7 foreign ministers in Lucca, Italy, on Tuesday. "We want to relieve the suffering of the Syrian people.

"Stockpiles and continued use demonstrate that Russia has failed in its responsibility to deliver on its 2013 commitment. It is unclear whether Russia failed to take this obligation seriously or Russia has been incompetent, but this distinction doesn't much matter to the dead."

Speaking about the future, Tillerson said, "Russia can be a part of that future and play an important role. Or Russia can maintain its alliance with this group, which we believe is not going to serve Russia’s interests longer-term."

"It is clear to all of us that the reign of the Assad family is coming to an end. But the question of how that ends and the transition itself could be very important in our view to the durability, the stability inside of a unified Syria.

"That’s why we are not presupposing how that occurs," he added.

Attending the G-7 conference were foreign ministers from Canada, France, Germany, Italy, Japan, the United Kingdom, and the United States, as well as Jordan, Qatar, Saudi Arabia, Turkey, and the United Arab Emirates.