( CNN ) -- Three Russian tanks and other military vehicles crossed the border into Ukraine on Thursday , prompting a skirmish between Ukrainian and Russian forces , acting Ukrainian Interior Minister Arsen Avakov said . The Russian Foreign Ministry told the BBC that the claim was `` another fake piece of information . '' According to Avakov , tanks crossed the border at a checkpoint controlled by pro-Russian separatists in the Luhansk region of eastern Ukraine . Armored vehicles and artillery were part of the columns , Avakov said , citing Ukrainian intelligence . Two of the tanks split off and headed in the direction of Gorlovka , also known as Horlivka , and were attacked by Ukrainian military forces , Avakov said . Part of that column was destroyed , he said . CNN has not independently confirmed the incidents . The countries have been engaged in a tense stand-off since March , when Russia annexed Crimea and massed troops along its border with Ukraine . U.S. officials said in late May that thousands of Russian troops had withdrawn from the border . Thousands more who remained appeared to be preparing to depart , U.S. officials said at the time . Western leaders have accused Moscow of fomenting instability in eastern Ukraine . Russian leaders say Ukraine has failed to move to implement a framework for peace worked out in Geneva , Switzerland , in April . They say Ukrainian leaders have carried out a campaign of violence against people living in the largely pro-Russian east . Also on Thursday , Ukrainian President Petro Poroshenko and Russian President Vladimir Putin `` held a substantial and long phone conversation , '' the Ukrainian President 's media office said , but it was unclear if that conversation occurred before or after the reported tank incursion . The leaders discussed Poroshenko 's peace plan to resolve the situation in the east of Ukraine , the media office said .
Russian tanks crossed border into Ukraine , Ukrainian Interior Minister Aresn Avakov says . A skirmish resulted , with Ukrainian forces attacking one column , Avakov says . - The U.S. State Department has warned Americans in Crimea to leave the peninsula and return home immediately because of a possible threat from Russia. Ukrainian President talked to Russian leader about peace plan , media office says .