What happens next in Ukraine?

Tough guy: Russian President Vladimir Putin has made a surprise intervention in Crimea. Source: News Corp Australia

UKRAINE is "on the brink of disaster", according to the country's newly installed Prime Minister Arseniy Yatsenyuk.

At the weekend Russian soldiers seized Ukraine's southernmost region of Crimea after a dramatic uprising forced Victor Yanukovych to flee the country.

Ousted: Ukrainian president Viktor Yanukovych. Picture: AFP Source: News Corp Australia

The soldiers arrived without warning and any identification. Until Sunday (Australian time) it was unclear who sent them.

The crisis is fast-moving but one thing hasn't changed. Ukraine is deeply divided into its western and eastern sides.

Pro-European leader Yulia Tymoshenko may run to be the next president of Ukraine. Picture: AFP Source: AFP

Protests camps in Ukraine's western capital, Kiev. Picture: AFP Source: AFP

Eastern residents prefer closer relations with Russia.

Most of Ukraine's Russian-speaking population live there and at the 2010 presidential election a majority voted for pro-Russian candidate Viktor Yanukovych.

West Ukraine tends to be much more pro-European. A majority voted for pro-European leader Yulia Tymoshenko in 2010 and most residents speak Ukrainian.

Russian navy vessels moored off the coast of the town of Limassol, in the Meditteranean island of Cyprus on February 27, 2014. Picture: AFP Source: AFP

Crimea is a particularly pro-Russian area. Almost 60 per cent of the population is ethnic Russian and the region is the home of the Russian navy's Black Sea Fleet.

That has led some international relations experts to wonder whether other pro-Russian towns will be invaded next.

Here are four popular predictions about what may happen next:

Human shield: A Ukrainian Orthodox Archbishop guards the gateto a Ukrainian military base in the village of Perevalne, outside of Simferopol, Ukraine. Picture: AP Source: AP

1. THE RUSSIANS INVADE FURTHER

And it could get bloody, the BBC's Bridget Kendall says :

The conflict is on a knife edge. The deployment of Russian troops in Crimea has not yet led to bloodshed.

But if that widens into a Russian military intervention into other parts of Ukraine, it is hard to see how violent clashes could be avoided.

In other southern and eastern towns pro-Russian protesters have already called for Russian intervention, writes Alexander Motyl from ForeignPolicy.com :

Adding fuel to the fire is the fact that pro-Russian forces have seized administrative buildings and called for Russian assistance in a variety of Ukraine's southern and eastern provinces: Kharkiv, Luhansk, Donetsk, Mykolaiv, and Dnipropetrovsk..

Both Moscow and Kiev know that Russia's military is superior to Ukraine's. Russian armed forces number about 750,000 troops; Ukraine's about 150,000. Russia has been aggressively spending on its military in the last decade, while Ukraine has actually been cutting back. In any armed conflict, Russia would win.

Is Putin willing to start a war over all or most of Ukraine, or will he confine himself to annexing Crimea or, say, a few south-eastern provinces?

2. THE INVASION STOPS IN CRIMEA

Ukrainian soldiers guard a gate to their military base in the village of Perevalne, outside of Simferopol. Picture: AP Source: AP

Russia could keep hold of Crimea and not invade the rest of Ukraine. Something similar has happened before.

In 2008, Russian forces invaded two provinces in the former USSR republic of Georgia.

The country's military forces seized the regions of South Ossetia and Abkhazia but the rest of Georgia remained independent, The Atlantic explains:

Many others are comparing the current situation to Russia's intervention in Georgia in 2008 over Abkhazia and South Ossetia, which also have small ethnic Russian populations.

Russia sent peacekeepers to the territories, and dispatched its military to ostensibly protect those troops when Georgia tried to reclaim South Ossetia by force in the summer.

That war lasted five days and left Russia in control of the provinces, both of which are now home to Russian military bases.

3. UKRAINE FIGHTS BACK:

Ukraine could instantly plunge Crimea into a black out, Slate writes:

The Crimea's dependence on Ukraine for nearly all of it electricity makes it equally vulnerable to nonviolent retaliation.

One suggestion making the rounds of the Ukrainian internet is that the mainland, with warning, shut off the power for 15 minutes. It may not normalise the situation, but it could give Moscow pause.

But that might not stop the Russians.

Of course, Russia could retaliate by cutting off Ukrainian gas supplies, but that would mean cutting off much of Europe as well.

And in terms of sheer military force, the Russians have many more soldiers than the Ukrainians:

4. A NEW COLD WAR

Not the best of friends: US President Obama and Russian President Putin. Picture: AP Source: News Corp Australia

It is considered unlikely that the US will intervene in the conflict.

At the weekend President Obama said: "There will be costs for any military intervention in Ukraine" but there has been no suggestion the superpower's considerable military might.

In a TV interview US Secretary of State John Kerry virtually ruled out military action.

"This is a time for diplomacy," he said. "And we will engage diplomatically as much as we can in order to steer this away from an increase in the tension in the level of the crisis."

But if the crisis ballooned into a regional war, Ukraine's neighbouring countries would call on America for help, Politico writes :

Any invasion — which is what it would be — of a vast country of 46 million in the heart of Europe, sharing borders with NATO allies Poland, Hungary, Slovakia and Romania, would pose a major security challenge for the United States and other key European powers.

Even without further Russian action, allies such as the Baltic countries will be seeking US reassurance ...

These countries likely will also ask for hard reassurances — such as deployments of US and other allied troops and equipment on their territory