The Economist: Many Westerners find Vladimir Putin’s war in Ukraine mystifying. It has brought Russia economic woe (sanctions and a shattered credit rating) and international isolation. Why fight so hard for a slice of another country’s rust-belt? Is it part of a sinister strategy to divide and weaken the West, an irrational outbreak of paranoia about an imagined outside threat to Russia, or a desperate attempt to distract domestic opinion from the regime’s political and economic failure?

The Kremlin has annexed the Crimean peninsula (the site of an important Russian naval base) and stoked a separatist rebellion in two of Ukraine’s easternmost provinces, Lugansk and Donetsk. The rebels, with strong Russian military and intelligence backing, have proclaimed “people’s republics” there and have continued to advance into the rest of Ukraine, in defiance of a ceasefire agreed in Minsk in September. Ukraine is losing the war and is desperate for financial and military help from the West. America is mulling arms deliveries, but holding back to see if a last-ditch Franco-German diplomatic deal can bring a truce. Few outside Russia believe the Kremlin’s justification for the war. Russians in Ukraine were not being persecuted. The government in Kiev is not “fascist” (extreme-right parties fare worse in Ukraine than they do in Western Europe). Far from menacing Russia, NATO countries have slashed defence spending, just as Russia is rearming. The three main theories about Vladimir Putin’s motivations could be summed up as “bad”, “mad” or “sad”.