US warns of new sanctions as high-stakes Ukraine talks loom

People sing the Ukrainian national anthem during a pro-Ukraine rally in the eastern Ukrainian city of Lugansk on April 15, 2014. The United States has threatened Russia with new sanctions ahead of high-stakes talks on the Ukraine crisis, as it backed
People sing the Ukrainian national anthem during a pro-Ukraine rally in the eastern Ukrainian city of Lugansk on April 15, 2014. The United States has threatened Russia with new sanctions ahead of high-stakes talks on the Ukraine crisis, as it backed Kiev's right to confront separatist uprisings in its volatile east. -- PHOTO: AFP

WASHINGTON (AFP) - The United States on Tuesday threatened Russia with new sanctions ahead of high-stakes talks on the Ukraine crisis, as it backed Kiev's right to confront separatist uprisings in its volatile east.

The US and the European Union are preparing for their first four-way talks with Ukraine and Russia on Thursday, although hopes are not high for any breakthrough at the Geneva meeting, amid a slew of failures in past weeks.

State Department spokesman Jen Psaki said that with Ukraine threatened with a split between its Russian-speaking east and EU-leaning west, it is hoped the talks could de-escalate tensions.

Priorities included trying to get Russia to demobilize pro-Kremlin militias, who have seized control of government buildings in 10 cities in Ukraine's southeast, although Moscow has denied any links to them.

But Ms Psaki made it clear that while the US hoped diplomacy would prevail, Washington and the EU were prepared to slap Moscow with tougher sanctions if no headway is made in Geneva.

"Not only do we anticipate additional sanctions at some point, we're preparing additional steps," she said, adding Secretary of State John Kerry had spoken Tuesday with his French, German, British and EU counterparts.

Fears are growing of armed clashes, which could trigger an all-out war, with an estimated 40,000 Russian troops massed on Ukraine's eastern border.

Ukraine rolled tanks toward a flashpoint eastern city on Tuesday to quash a separatist surge backed by Moscow - a high-risk operation that was sharply condemned by the Kremlin but won Washington's support.

The 20 tanks and armored personnel carriers were the most forceful response yet by the Western-backed government in Kiev to the occupation of state buildings across Ukraine's rust belt.

Russian Foreign Minister Sergei Lavrov and his Ukrainian interim counterpart Andriy Deshchytsya will Thursday have "the first opportunity to engage... at the same table, with the EU, with the United States," she said.

"We feel there should always be an opportunity and an opening for diplomacy," Psaki insisted, saying an "off-ramp" still existed for Moscow.

Constitutional reform for Ukraine could also be on the agenda, she said, noting: "These are priorities that even the Russians have said they support."

Russian Prime Minister Dmitry Medvedev warned Tuesday his western neighbor was "on the brink of civil war - it's frightening."

But the White House said Ukraine faced an "untenable" situation over the uprisings.

"We understand the government of Ukraine is working to try to calm the situation in the east and note the measured approach of the Ukrainian security forces thus far," White House spokesman Jay Carney said.

While force was "not a preferred option," Mr Carney said, "the Ukrainian government has a responsibility to provide law and order, and these provocations in eastern Ukraine are creating a situation in which the government has to respond."