In a move considered aggressive by US and European officials, Russia has sent at least 12 warships to patrol waters near its naval base in Tartous, Syria.

The deployment appears to be a warning to Israeli and Western officials against military intervention in Syria’s bloody civil war, which has now claimed the lives of over 80,000 people.

Russia’s increased presence in the region — which began raising eyebrows in the US three months ago — represents one of its largest sustained naval deployments since the Cold War, the Wall Street Journal reported on Thursday.

“It’s a show of force. It’s muscle flexing,” a top US official told the Journal.

Russian news sources reported earlier Thursday that five warships had entered the Mediterranean Sea to bolster the country’s new regional task force. The vessels were scheduled to dock in Limassol, Cyprus.

In March, Russian Defense Minister Sergei Shoigu announced that the naval task force was needed in order to protect Russian interests in the region.

Also Thursday, Russia’s Foreign Minister Sergey Lavrov shrugged off Israeli pleas not to sell sophisticated S-300 air defense systems to Bashar Assad’s regime, saying Moscow would fulfill its contract with Damascus. Prime Minister Benjamin Netanyahu reportedly warned Russian President Vladimir Putin, in emergency talks on Tuesday, that the sale could push the region toward war.