American officials disclosed Sunday that at least seven giant Russian Condor transport planes had taken off from a base in southern Russia during the past week to ferry equipment to Syria, all passing through Iranian and Iraqi airspace.

Their destination was an airfield south of Latakia, Syria, which could become the most significant new Russian military foothold in the Middle East in decades, American officials said…

“There were military supplies, they are ongoing, and they will continue,” Mr. Lavrov was quoted as saying by Russian news agencies. “They are inevitably accompanied by Russian specialists, who help to adjust the equipment, to train Syrian personnel how to use this weaponry.”…

American diplomats raised the issue with the Iraqi government on Sept. 5, hoping that the Iraqis would follow Bulgaria’s example and declare their airspace off limits to the Russian transport planes.