Russian invasion fears grow over Ukraine
Fears are growing of a fresh Russian incursion into Ukraine as world leaders prepare to discuss the crisis at a summit.
US General Philip Breedlove raised the prospect that the Kremlim could even seek to take control of a Russian-speaking section of nearby Moldova.White House deputy national security adviser Tony Blinken echoed the suggestion that Vladimir Putin could be plotting further action.
"It's deeply concerning to see the Russian troop buildup on the border," Mr Blinken told CNN.
"It creates the potential for incidents, for instability.
"It's likely that what they're trying to do is intimidate the Ukrainians... It's possible that they're preparing to move in."
The latest escalation in tensions came on the eve of the gathering at the Hague.
David Cameron and other premiers were originally meant to be attending a Nuclear Security Summit, but Barack Obama has upgraded it to discuss the confrontation with Moscow.
General Breedlove raised concerns about the position of Transnistria, a restive part of western Moldova where separatists have already demanded to join Russia.
It declared independence in 1990 but has not been recognised by the international community.
Speaking at an event held by German Marshall Fund think-tank, he said the Kremlin might view the region as the "next place where Russian-speaking people may need to be incorporated".
"There is absolutely sufficient force postured on the eastern border of Ukraine to run to (Transnistria) if the decision was made to do that , and that is very worrisome," General Breedlove said.
In an article for the Sunday Telegraph, Foreign Secretary William Hague insisted European nations should not "run scared" of Moscow's "bullying behaviour" in Ukraine.
He warned Moscow it was not simply facing the "short-term pain" of limited sanctions, but long-term "isolation and stagnation".
Part of that could be a fundamental rethink by the West of its energy sources, including accessing shale gas reserves through 'fracking'.
Mr Hague also cautioned that the spread of Russia's "oligarchic" system could undermine European democracy.
"Russia has been damaged by its failure to develop independent institutions and by an oligarchic economic system," he said.
"There is an evident danger of some of the same corrupting habits spreading into democratic countries."
In South East Europe and the Balkans in particular, we are seeing the creation of concentrations of economic, political and media power which could inhibit the development of genuine or stable democracy and reverse progress already made.
"If this is allowed to go unchecked, European democracy could be damaged and undermined over the long term."
Moscow's ambassador to the EU Vladimir Chizhov told the BBC Moscow did not have any "expansionist views" and that "nobody should fear Russia".