On 25 December 1991, Mikhail Gorbachev, the leader of the Soviet UnionOfficially the Union of Soviet Socialist Republics (USSR). A powerful group of communist republics, the biggest being Russia, that existed from 1922 to 1991. , addressed the people: "We are now living in a new world".

Overnight, a superpower disappeared. The Cold War was over.

History has come crashing back. On Thursday, Russian president Vladimir Putin ordered his tanks to attack Ukraine. By Saturday, missiles were hitting Kyiv. Yesterday, fighting broke out in the streets of KharkivUkraine's second-largest city. Before the war, it had a population of 1.5 million.. Hundreds have been killed.

Reports suggest that defence has been stronger than expected. For Putin, this might not matter. Many believe he will not stop until the USSR is back.

The USSR was founded in 1917 by a group of revolutionaries. They wanted to overthrow the tyranny of the Tsars.

Vladimir Lenin's government quickly became totalitarianWhen a political system or leader requires complete subservience to the state. In a totalitarian system, people are not allowed to express their own opinions.. Under him and Stalin, the USSR and its agents committed numerous atrocities.

The KGB spied on Soviet citizens. Dissenters were killed or sentenced to work in bone-crushing labour camps.

Religion was banned and poverty was rampant. Millions of Ukrainians died in a famine. 

Things softened under Stalin's successor Nikolai Khrushchev - but only a little. In 1956 he sent tanks to crush protestors in Hungary. And in 1962 brought the world to the brink of nuclear war during the Cuban Missile CrisisA confrontation between the US and the Soviet Union that occurred after the USSR installed missiles on the island of Cuba, within 140km of Florida..

Many breathed a sigh of relief when the USSR collapsed. In Russia, the picture is complicated. A 2020 poll found that 75% of Russians consider the Soviet Union the "greatest time" in their country's history - though only 28% want to return to it.

Putin once said: "Whoever does not miss the Soviet Union has no heart. Whoever wants it back has no brain."

In the past decade, he has made a series of threatening moves against his ex-Soviet neighbours. He has also brought back USSR-style oppression, with protestors and political opponents arrested. 

The strategy is reminiscent of that pursued by the Soviet Union, but expert Kathryn Stoner points out one crucial difference: "It's not about ideology, just money and mutual convenience".

And it might be difficult to replicate the USSR. Three former Soviets - Estonia, Latvia and Lithuania - are part of the EU and NATOThe North Atlantic Treaty Organisation was founded in 1949 to unite Western democracies in Europe and North America against the perceived growing threat of the USSR. It now has 31 members.. To absorb them would risk nuclear war.

The Iron CurtainA political, military and ideological barrier dividing Europe into two separate areas from the end of World War Two until the end of the Cold War in 1991.  was almost impenetrable. Soviet citizens were kept ignorant of life outside. It is difficult to achieve that in the internet age.

Yes: Putin will not call his state the Soviet Union. But his invasion of Ukraine and recent aggressive behaviour towards ex-Soviet neighbours shows he is hungry for a new Russian empire.

No: The Soviets were revolutionaries. They sought originally to free people from tyranny and inequality. Putin's state has no noble ambitions whatsoever. 

Or... Russia is badly run, impoverished and increasingly irrelevant on the global stage. Even if a new Soviet Union arises, it will be a mere shadow of its fearsome former self, liable to crumble quickly.