PRESIDENT VLADIMIR PUTIN, his bitter resentment at the Soviet empire’s collapse metastasized into seething Russian nationalism, has marginalized the political opposition, muzzled dissidents and intimidated independent voices in civil society. In prosecuting his widening war in Ukraine, he has also resurrected the tyranny of the Big Lie, using state-controlled media to twist the truth so grotesquely that most Russians are in the dark — or profoundly misinformed — about events in their neighbor to the west.

Most Russians get their news from state-

controlled broadcast outlets, which have moved beyond mere propaganda into outlandish conspiracy theories and unhinged jingoism. The shoot-down of the Malaysian airliner in July, over territory controlled by Russian-sponsored militias in Ukraine, was spun by Kremlin’s media mouthpieces into a provocation orchestrated by the West. With few countervailing views in the mainstream media, many Russians believed the spin or had no idea what to believe.

In support of those Russian-sponsored militias in eastern Ukraine, now backed by growing ranks of Russian troops and weapons, Moscow has created a fantasy that plays on Russian victimization. By this rendering, the forces backing Ukraine’s government in Kiev are fascists and neo-Nazis, a portrayal that Mr. Putin personally advanced on Friday, when he likened the Ukrainian army’s attempts to regain its own territory to the Nazi siege of Leningrad in World War II, an appeal meant to inflame Russians’ already overheated nationalist emotions.

In the absence of independent and free reporting, few Russians realize that Russian soldiers and armaments are in action in eastern Ukraine, albeit (as in Crimea) in uniforms and vehicles stripped of their identifying insignia and license plates. With no free media, Russians are left to fend for themselves against a firestorm of falsehoods.

Only a few trickles of real information are penetrating Mr. Putin’s barrage of lies. In The Post on Friday, reporter Karoun Demirjian described the trauma of Russian mothers whose soldier sons were captured last week in Ukraine — a country where they had no idea Russian troops had been deployed. The mothers, demanding explanations, have been met with stonewalling and indifference from Russian authorities.

Mindful of polls suggesting Russians do not support armed intervention in Ukraine, Mr. Putin pretends Moscow’s forces are uninvolved. But by driving domestic public opinion into a frenzy through the state-controlled media, he could be preparing Russians for more overt and wide-

ranging intervention.

Against the extensive propaganda instruments available to Mr. Putin’s authoritarian regime, the West can promote a fair and factual version of events, but there’s little it can do to make ordinary Russians believe it. Even in a country with relatively unfettered access to the Internet, the monopolistic power of state-controlled media is a potent weapon in the hands of a tyrant.

Mr. Putin’s Big Lie shows why it is important to support a free press where it still exists and outlets like Radio Free Europe that bring the truth to people who need it.