Russia's upper house of parliament voted on Tuesday to extend the military's lease of its naval base in Tartus, Syria, by a further 49 years.

Following the vote, Russia's Defense Minister Sergei Shoigu announced plans to drastically expand the Mediterranean naval facility, creating space to keep 11 warships, including nuclear vessels.

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"Last week the Commander-in-Chief (Russian President Vladimir Putin) approved the structure and the bases in Tartus and in Hmeimim (air base)," Shoigu is quoted of telling a group of military officials. "We have begun forming a permanent presence there."

According to Russian media, the Tartus naval facility is currently only large enough to keep one Russian warship, the "Pyotr Velikiy."

As part of the agreement, Russia will also have indefinite access to the Hmeimim air base, from which it launched numerous airstrikes on Syrian rebel forces over the past two years.

Russia and Syria had initially agreed to a deal on permanent military bases back in back in January, although it was only formally endorsed by Russia's lower house last week and the upper house, otherwise known as the Federation Council, on Tuesday. The final agreement must still be signed by Putin before it comes into effect.

Russia announced partial troop withdrawal

Russia has kept a military presence at Tartus since the 1970s and maintained close relations with Syria following the breakup of the Soviet Union.

More recently, Russia has since 2015 been the main military backer of Syrian President Bashar al-Assad during country's long and multipronged civil war. Russia's air campaign against Syrian rebel groups and "Islamic State" (IS) militants were the deciding factor in turning the tide of the Syrian civil war in Assad's favor.

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Along with Iran and Turkey, Russia has brokered localized ceasefire agreements between the Syrian military and rebel factions. That has seen marked drop in the violence, although Assad's forces have continued to rack up the pressure on insurgent-held pockets on the outskirts of the capital, Damascus, and the northwestern rebel-held Idlib province.

Earlier this month, Putin announced a partial pullout of Russian troops from Syria, saying the military had accomplished its mission of defeating IS in Syria. Russia would now shift its focus to stabilizing the besieged country, Putin added.

dm/jm (AP, Reuters, dpa)