While pro-Russian and pro-Western media have been spinning the Crimea crisis as either a heroic exercise in righting a past wrong or a land grab by a new Hitler, the legal position is far from straightforward.
Crimea was once an independent Tatar khanate, captured by Russia in the 18th century. The Tatars were deported by Stalin as punishment for alleged collaboration with the Nazis — although some fought on either side in World War II. In 1954, Nikita Khruschev (then Soviet leader), gifted the territory to Ukraine. The decision was of no practical consequence at the time since both Russia and Ukraine were simply states within the USSR. There was, however, no public (or even parliamentary) consultation.
In the Gorbachev era, many Tatars returned. They now form about 12 per cent of the population (about 60 per cent are Russian, the remainder Ukrainians, Bulgarians etc.). Strategically, Crimea is important for its natural resources and its ice-free, deepwater port of Sevastopol, a major base of Russia's powerful Black Sea Fleet.
The international law claims are as complex as the history.
The US and its allies are right to note that, since the Kellogg-Briand Pact of 1928 (later embodied in the UN Charter), borders may no longer be changed by force.
The Russian answer (equally true) is that it is not clear that Ukraine ever validly acquired title to Crimea — it seems the peninsula's status was papered over after the USSR's dissolution. A number of declarations of autonomy, clashes and de facto compromises in the following five years left Ukraine holding the territory and most naval facilities, but gave Russia the bulk of the fleet anchored there, a lease of the port of Sevastopol and the right to station up to 25,000 troops in Crimea.
In addition, Russia claims to be defending its nationals by intervening in the dispute. This, too, is murky. While defence of nationals is a kind of self-defence (and a traditional justification for use of force), it is not clear that Russians in Crimea were endangered. Certainly, no direct threats had been made against them. On the other hand, a pro-Russian Ukranian government had just been ousted by force, and the new government's first act (later vetoed by the new president) was to strip Russian of its status as regional language.
All of this seems to have created a great deal of mistrust among ethnic Russians as to the new government's intentions, doubtless inflamed