Ukraine crisis: US raises pressure on Russia over deal
The US has threatened tougher economic sanctions if Russia fails to abide by a new international agreement to help de-escalate the crisis in Ukraine, the BBC reported.
The Kremlin responded by accusing the White House of treating Moscow like a "guilty schoolboy" over the deal.
Meanwhile, Ukraine's foreign minister said "anti-terrorist" operations in the east would be put on hold over Easter.
Pro-Russian separatists in several cities are refusing to leave buildings, defying a key term of the accord.
Russia, Ukraine, the EU and US had agreed during talks in Geneva that illegal military groups in Ukraine must be dissolved, and that those occupying government premises must be disarmed and leave.
The sides also decided there would be an amnesty for all anti-government protesters.
But the separatists' spokesman in the city of Donetsk said that the Kiev government was "illegal", and vowed they would not go until it stepped down.
The protesters also insisted that pro-European Union demonstrators in Kiev's Maidan Square - the vanguard of the protest movement that toppled President Viktor Yanukovych, an ally of Moscow - had to pack up their camp first.
After cautiously welcoming the deal struck on Thursday, the White House has now stepped up pressure on Russia to use its influence over separatists occupying the buildings in nine cities and towns in eastern Ukraine.
On Friday, US National Security Adviser Susan Rice warned that if Moscow failed to uphold the deal a new round of sanctions would focus on what she called "very significant sectors of the Russian economy."
"We believe that Russia has considerable influence over the actions of those who have been engaged in destabilising activities in eastern Ukraine," she told reporters at a news briefing in Washington.
US Secretary of State John Kerry spoke to Russian counterpart Sergei Lavrov by telephone on Friday.
A senior US state department official said Mr Kerry had made it clear "that the next few days would be a pivotal period for all sides to implement the statement's provisions."
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