Foreign ministers from the Group of Seven (G7) major industrialized nations met in Italy on Monday, looking to put pressure on Russia to break its ties with Syrian President Bashar al-Assad.

In a shift in Washington’s strategy, U.S. missiles hit a Syrian air base last week in retaliation for what the United States and its allies say was a poison gas attack by Syria’s military in which scores of civilians died. The Syrian government has denied it was behind the assault.

U.S. President Donald Trump had previously appeared disinclined to intervene against the Syrian leader and the attack raised expectations that he might now be ready to adopt a tougher-than-expected stance with Russia, Assad’s main backer.

Calling the strike a “game changer,” British Foreign Secretary Boris Johnson said support for the Syrian president “was toxifying the reputation of Russia” and suggested sanctions could be imposed on Moscow if it refused to change course.

U.S. Secretary of State Rex Tillerson is due to travel to Moscow on Tuesday at the end of the two-day gathering in the Tuscan city of Lucca with his Italian, German, French, British, Japanese and Canadian counterparts.

Read the whole story from Reuters.