Russia's latest movements on the ground suggest it's plan to set up a forward air operating base at an airfield in Syria, acorrding to the United States government, on Monday.
"We have seen movement of people and things that would indicate that they plan to use that base there, south of Latakia, as a forward air operating base," Pentagon spokesman Captain Jeff Davis said, according to Telegraph.
The Pentagon, however, declined to give specific details about the Russian build up in Syria.
The Pentagon's statement on possible Russian forward air operating base in Syria came a day after Britain based Syrian Observatory for Human Rights said Russian forces were building a long runway capable of accommodating large aircraft near the Hemeimeem military airport in Syria's coastal province of Latakia, according to Radio Free Europe.
Syrian Ambassador to Russia, Riad Haddad, refuted the presence of Russian troops in Syrian territory.
"We have been cooperating with Russia for 30-40 years in various areas, including the military sphere. Yes, we receive arms, military equipment, all this is done in line with agreements sealed between our countries. But the talk of your (Russian) troop presence on Syrian territory is a lie spread by Western countries, the United States," Haddad said on Monday, according to Reuters.
Russia also downplayed it's military role in Syria and maintained that the arms deliveries to Assad's regime designed for countering the ISIS.
"The arms transferred to the Syrian army are designed for countering the terrorist threat. Assad's forces bear the brunt of fighting the Islamic State on the ground," Russian foreign ministry spokeswoman Maria Zakharova said, according to Wall Street Journal.
