The United States on Monday followed through with its threat to formally suspend talks with Russia over the protracted conflict in Syria, accusing the Kremlin of joining with the Syrian Air Force in carrying out a brutal bombing campaign against the besieged city of Aleppo.
Anticipating the end of the talks after repeated warnings from American officials, President Vladimir V. Putin of Russia responded by withdrawing from a landmark arms control agreement that calls for each side to dispose of 34 tons of plutonium, a material used in nuclear weapons.
“Cooperation over Syria was the Obama administration’s last and best shot for arresting the downward spiral in the bilateral relationship with Russia,” said Andrew S. Weiss, a former White House expert on Russia who is vice president for studies at the Carnegie Endowment for International Peace. “The mistrust and hostility toward the United States by the Russian leadership is real and growing. It is going to be the driving force behind Russian external behavior for many years to come.”
In recent days, Russian and Syrian aircraft have carried out attacks, mainly in Aleppo, using bunker-busting bombs, incendiary munitions, cluster bombs, barrel bombs and thermobaric bombs, which produce devastating blasts, according to American intelligence officials. About 275,000 civilians are trapped in those areas, including an estimated 100,000 children. Hundreds of people in those areas have been killed in the past week, international aid groups say.
“Unfortunately, Russia failed to live up to its own commitments,” the statement added. “Rather, Russia and the Syrian regime have chosen to pursue a military course, inconsistent with the cessation of hostilities, as demonstrated by their intensified attacks against civilian areas,” which American officials say has included hospitals.
But Mr. Putin had a move of his own. Saying relations with the United States had deteriorated in a “radically changed environment,” he issued a decree suspending his country’s participation in an agreement on the disposal of plutonium that was concluded in 2000 as one of the framework disarmament deals of the early post-Cold War period.