Ukraine crisis: US threatens further sanctions on Russia if stalemate continues as Moscow says it 'cannot be treated like a guilty schoolboy'

Washington has threatened further sanctions on Moscow if the stalemate over resolving the crisis in Ukraine continues, accusing Russia of not using perceived influence over pro-Russian separatists in the east of the country to instruct them to vacate government buildings and lay down weapons.

But Russia continued its insistence that it has no control over the “little green men” who, in combat gear and with automatic weapons seized public buildings in over 10 cities in eastern Ukraine - a denial that Western allies of those who overthrew the pro-Russian president in Kiev do not accept.

Early progress made through talks in Geneva between Ukraine’s Kiev based interim government, Russia, the US and EU was reversed on Friday after the pro-Russian insurgents occupying the buildings refused to leave until the interim government resigns, claiming that they too are occupying government offices.

The US warned of heavier economic sanctions than those already imposed over Crimea if Moscow failed to uphold the Geneva deal, which calls for all sides to work to ‘de-escalate tensions and restore security for all citizens’.

“We believe that Russia has considerable influence over the actions of those who have been engaged in destabilising activities in eastern Ukraine,” national security adviser Susan Rice said.

“If we don't see action commensurate with the commitments that Russia has made yesterday in Geneva... then obviously we've been very clear that we and our European partners remain ready to impose additional costs on Russia.

“Those costs and sanctions could include targeting very significant sectors of the Russian economy.”

President Vladimir Putin's spokesman Dmitry Peskov hit straight back, asserting: “You can't treat Russia like a guilty schoolboy. That kind of language is unacceptable.”

He also voiced scepticism - of a kind also heard from the Ukrainian government - about how useful the cautiously worded Geneva pact would be.

The Russian Foreign Ministry said: “The Americans are once again stubbornly trying to whitewash the actions of the Kiev authorities, who have embarked on a course of violently suppressing protesters in the southeast who are expressing their legitimate indignation over the infringements of their rights.”

Later in the day, US Secretary of State John Kerry called Russian Foreign Minister Sergei Lavrov and urged “full and immediate compliance” with the Geneva agreement, a senior State Department official said.

“He made clear that the next few days would be a pivotal period for all sides to implement the statement's provisions, particularly that all illegal armed groups must be disarmed and all illegally seized buildings must be returned to legitimate owners,” the official said.

The crisis has caused the worse East-West tensions since the end of the Cold War, but Russian President Vladimir Putin said today he sees no obstacles to improving relations with the West.

Mr Putin welcomed NATO's selection of former Norwegian Prime Minister Jens Stoltenberg as its new head, saying on Saturday the pair had “very good relations” but that it was up to the West to improve ties.

In an interview on state television also shown Saturday, Putin was asked whether relations with the West would improve by the end of the year.

“This doesn't depend on us, or not only on us. It depends on our partners,” Putin said, according to the ITAR-Tass news agency.

“I consider that there is nothing that would impede normalisation and normal cooperation,” he added.

Additional reporting from agencies