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Ukraine Ends Easter Truce With Pro-Russia Separatist Groups

"We have obtained the support of the United States, that they will not leave us alone with an aggressor," Ukraine’s first deputy prime minister says.

Ukraine’s government formally ended an Easter truce and is relaunching an "anti-terrorist operation" to eliminate armed pro-Russian separatist groups, it announced Wednesday – hours after Vice President Joe Biden left Kiev.

"We have obtained the support of the United States, that they will not leave us alone with an aggressor,” Ukraine’s First Deputy Prime Minister Vitaly Yarema said, according to Reuters. “We hope that in the event of Russian aggression, this help will be more substantive."

Yarema, who has a role in security matters, told reporters on the sidelines of a weekly Cabinet meeting the new action was not yet underway, but added: "In the near future, appropriate measures will be taken and you will see results."

The developments raised fears that last week's international agreement on easing Ukraine's crisis was unraveling.

Secretary of State John Kerry spoke on the phone with Russian Foreign Minister Sergey Lavrov Tuesday, expressing concern at mounting evidence that separatists are continuing to increase the number of buildings under occupation and take captive journalists and other civilians.

Kerry said that Washington would impose further sanctions on Russia if tensions did not de-escalate in eastern Ukraine.

Moscow denies it is orchestrating the militants, who say they want the chance to join Crimea in becoming part of Russia following the overthrow of Moscow-backed President Viktor Yanukovich after months of street protests in Kiev.

Reuters contributed to this report.

Alastair Jamieson