PARIS — Russia said late Thursday that the Syrian military has suspended its combat operations in eastern Aleppo to allow civilians to leave the city and that it had reached agreement with the United States to negotiate the safe departure of rebel fighters. A senior U.S. State Department official here traveling with Secretary of State John Kerry said that neither of those assertions could yet be confirmed but that Kerry was in contact with Russian Foreign Minister Sergei Lavrov. There were conflicting reports from inside Aleppo, where some residents reported a sudden quiet, but others said neighborhoods were still under fire.