The United States on Monday suspended talks with Russia on the Syrian conflict, accusing it of bombing civilian areas in the country, BBC reported. The decision came a week after Washington said it would halt talks unless Moscow stopped bombing the city of Aleppo, which has seen heavy fighting between forces loyal to Syrian president Bashar al-Assad and rebel groups.

US State Department spokesperson John Kirby said Russia had “failed to live up to its own commitments” regarding the ceasefire between Syrian government forces and rebel outfits. Kirby said Moscow and Assad’s troops had targeted “critical infrastructure such as hospitals, and preventing humanitarian aid from reaching civilians in need”. “This is not a decision that was taken lightly,” the spokesperson said.

Denying the accusations, Moscow said it regretted the decision, adding that Washington was trying to shift the blame for renewed fighting between the two sides on to it. Russian foreign ministry spokesperson Maria Zakharova said the US had failed to “fulfil the agreements” regarding the ceasefire. Meanwhile, Russian president Vladimir Putin suspended a deal between the two countries on the disposal on weapons-grade plutonium, according to AP. The decree to suspend the deal cited the US’ “unfriendly actions” toward Russia as well as its inability to meet the obligations required by the disposal agreement.

Fighting between the two sides has intensified after a September 9 ceasefire between the pro-Assad side and rebel camps was called off two weeks ago. The ceasefire had ended after an aid convoy was bombed in north Aleppo. More than 300,000 people have died in the six-year-long civil war, and nearly half the country’s population forced to flee since it began. While the United States supports rebel groups, Moscow is seen as a key Assad ally.