The bill says photos, videos and other material uploaded to the internet can reveal military details useful to an enemy. Automatic geolocation can show where a military unit is deployed.

The bill affects "contract" soldiers, who can be sent abroad, not conscripts.

Russian soldiers' posts have revealed forces deployed to Ukraine and Syria.

For example, in July 2014 the BBC's Myroslava Petsa retweeted a post by a Russian soldier who proudly reported delivering Grad rockets to the pro-Russian rebels in Ukraine.

Russia annexed Ukraine's Crimea peninsula in March 2014 and the following month the rebels seized a big swathe of Donetsk and Luhansk - mainly Russian-speaking regions in eastern Ukraine.

Ukraine and Western governments accuse Russia of supplying heavy weapons and troop reinforcements to the rebels. Russia admits that some Russian "volunteers" are helping the rebels, but denies sending regular forces.

In a YouTube video a reporter for Vice News, Simon Ostrovsky, revealed how a Russian soldier's social media posts had enabled him to confirm the Russian military's direct role in the eastern Ukraine fighting.

In August 2014 an article by the Bellingcat investigative team said social media posts by Russian soldiers had confirmed deaths among members of Russia's 76th Airborne regiment in eastern Ukraine. The regiment is based in Pskov, western Russia.

Bellingcat specialises in analysis of social media to document conflicts, including Russia's military role in Syria.

So-called Islamic State (IS) runs a sophisticated social media operation. The jihadists are fighting not only the US-led coalition in Iraq and Syria, but also the Russian forces allied with Syrian government troops.

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The Russian defence ministry says two state security bodies - the FSB and FSO - already ban their staff from posting social media content about themselves or their work.

The new ban affecting armed forces personnel is expected to take effect in January 2018, Tass news agency reports.

Ukraine's military is also concerned about its soldiers revealing too much on social media.

The Kyiv Post reported those concerns in 2015, when the fighting with pro-Russian rebels was more intense.

"There have been cases where positions were revealed, which led to active shelling," said Dmytro Podvorchansky of Ukraine's Dnipro-1 Regiment.