Beirut: Russian forces are expanding the tarmac of a major airport in Syria's coastal province of Latakia, a stronghold of President Bashar Assad and his minority sect, a prominent Syrian monitoring group said on Sunday.
The report comes amid rising concern among US officials of increased Russian military activity in Syria.
President Barack Obama cast the buildup as an effort to prop up the country's embattled leader, warning Moscow against doubling down on Assad.
Russia, a longtime backer of Syria's government, denies it's trying to bolster Assad and says its increased military activity is part of the international effort to defeat the Islamic State group which has wreaked havoc in Syria and Iraq.
Today, the Russian foreign minister called for the international community to include the Syrian government in efforts to fight IS.
A former Lebanese general with knowledge of the Syrian military told The Associated Press last week that there are plans to build a military base in the coastal town of Jableh, about 25 kilometres south of Latakia city, where the airport currently under development is located. Israeli officials also say the aim appears to be a military base.
The airport, known by its old name Hemeimeem, already houses a military base and has come under shelling from advancing militants in the countryside.
After the Damascus airport, it's the most important functioning government-controlled airport in Syria. Officially named the Basel al-Assad International airport, after the president's brother who died in a car accident in 1994, it has one terminal, according to the Syrian Civil Aviation Authority website. The tarmac is currently 2,800 metres long and 45 metres wide.
The head of the Britain-based Syrian Observatory for Human Rights, Rami Abdurrahman, said witnesses, including officials inside the airport, reported that the tarmac was being expanded, apparently to allow for larger planes.
"It could mean there will be more supplies or that they want to turn it into an international airport," Abdurrahman said.
Witnesses told the Observatory no Syrian military or civilian officials are allowed near the tarmac. Abdurrahman said there are other plans to develop another rural airport east of Latakia city.
The Observatory relies on a network of activists on the ground to report on the Syrian civil war, now in its fifth year.
More than 250,000 people have been killed and nearly half of Syria's pre-war population of 23 million has been displaced from their homes. About 4 million of them are refugees in neighboring countries.