“If we are talking about them taking some sort of restrictive or prohibitive measures on the Americans' request, then this raises questions about their sovereign right to take decisions about planes from other countries — Russia in particular — crossing their airspace,” Russia’s deputy foreign minister Mikhail Bogdanov told the Interfax news agency.
“We explain where our planes are flying to, and what their purpose and their cargo is,” he added.
He said that ferrying cargo, which included humanitarian and military aid, through the airspace of a third party — as well as obtaining permission to do so — should be a routine procedure.
“We've never had any problems before,” he said.
Athens has said it is examining the U.S. request, but gave no further details. Washington is concerned that Moscow could be increasing its military support to Assad, an issue raised by Secretary of State John Kerry with Russian counterpart Sergei Lavrov during the weekend.
Russia has dismissed U.S. concerns about its alleged Syria buildup, saying its military aid to the Assad regime is nothing out of the ordinary. Likewise, Syria has denied reports of increased military activity by Russian troops on its soil.
Speaking late on Monday to Hezbollah's Al-Manar television station, Information Minister Omran Zohbi dismissed the reports as baseless.
“There is absolutely nothing to these rumors and what was said a few days ago,” Zohbi said of reports of increased aid from Russia.
“There are no Russian forces, and there is no Russian military activity on Syrian territory by land, sea or air,” Zohbi told Al-Manar.