Ukraine set to form new defence force

Ukraine is set to form a National Guard against Russia's expansionist threat after US President Barack Obama gave firm backing to the new leader from Kiev in a hardening Cold War-style standoff with the Kremlin.

The Verkhovna Rada parliament was expected to support the initial mobilisation of reservists and creation of a new force of at least 20,000 volunteers who could keep Russian troops from advancing beyond the Crimean peninsula they seized at the start of the month.

National Security and Defence Council chief Andriy Parubiy said the new guard would "ensure state security, defend the borders, and eliminate terrorist groups" - a term many in Kiev use to call the well-armed militias who patrol Crimea alongside Russian troops.

The flaring crisis on the eastern edge of Europe was sparked by the ouster last month of a pro-Kremlin regime that prompted President Vladimir Putin to seek and win the right to use force against a neighbour for the first time since a brief 2008 war with Georgia.

The new more nationalist but pro-European team that rose to power in Kiev on the back of the deadly popular uprising is viewed with derision by Putin and increasing warmth by leaders in the West.

Putin's March 1 decision to order troops into Crimea for the "protection" of the Russian-speaking majority there now threatens to bring down waves of political and economic sanctions that could leave the Kremlin more isolated from the West than at any point since the 1989 fall of the Berlin Wall.

But Russia's parliament is still due to consider legislation next week simplifying the process for the annexation of Crimea - a strong possibility after the Black Sea region holds a hotly disputed referendum on Sunday on switching over to Kremlin rule.

The European Union is due to consider travel bans and asset freezes on Monday against Russian officials held responsible for threatening Ukraine's territorial integrity.

Brussels is also expected next week to offer Ukraine a chance to sign an historic EU trade pact whose abrupt November rejection in favour of closer ties with Russia sparked the initial wave of Kiev unrest.

The White House has been moving on punitive measures faster than its European allies - their financial and energy sectors intertwined tightly with Russia - and has already approved visa restrictions and financial penalties on Moscow officials.

But US President Barack Obama told Ukraine's visiting Prime Minister Arseniy Yatsenyuk that Washington was willing to move much further if Putin failed to soften his stance immediately.

"There's another path available and we hope President Putin is willing to seize that path," Obama told reporters after awarding Yatsenyuk - whose legitimacy Putin rejects - the honour of a government leader by meeting him in the Oval Office.

"But if he does not, I'm very confident that the international community will stand firmly behind the Ukrainian government."

And Obama made plain where he stood on Russian troop movements in Crimea that began at the start of the month.

"We have been very clear that we consider the Russian incursion into Crimea outside of its bases to be a violation of international law," Obama stressed.

"And we have been very firm in saying that we will stand with Ukraine and the Ukrainian people in ensuring that territorial integrity and sovereignty is maintained."