Iran is building a permanent military base in Syria, the BBC reported on Friday, citing ‘a Western intelligence source.’

According to the report, the base is being built within a compound used by the Syrian military near the city of Al-Kiswa, located some 13 kilometers south of the war-torn country’s capital, Damascus, The Haaretz reported.

Aerial images of the site referenced by the source dated January, May and October of this year show that construction at the compound has developed; since January, at least three new buildings have been erected, while two of the existing structures have undergone renovation. 

The original compound, which consists of around 25 buildings, is said to likely house soldiers and vehicles.

According to the report, however, ‘it is not clear whether the facility is currently occupied,’ nor is it possible ‘to independently verify the purpose of the site and the presence of the Iranian military.’

For the past year, Israel has been warning about Iran entrenching itself in Syria. Prime Minister Benjamin Netanyahu and Defense Minister Avigdor Lieberman have warned several times that Israel could be forced into military action under such circumstances.

Netanyahu told the BBC on Sunday that Iran is seeking to use its close ties with Syria to dock its submarines in Syrian ports. After his meeting with Russian President Vladimir Putin in March, Netanyahu said that Iran was seeking to lease naval facilities along Syria’s Mediterranean coast, as Russia had done at the port of Tartus. 

Last month, Netanyahu stressed to Russian Defense Minister Sergey Shoygu that Israel would not allow the Iranian military to gain a foothold in Syria.