WASHINGTON (AP) — Vice President Joe Biden and Ukrainian President Petro Poroshenko say they’re concerned about Russia’s suggestion that so-called Russian “peacekeepers” could play a role in Ukraine.

Biden and Poroshenko spoke by phone on Wednesday. The White House says Poroshenko told Biden that Russia was directly involved in the conflict, referring to Ukrainian forces being fired on from Russia’s side of the border. The two leaders said they were also concerned about Russia’s military buildup along the border and weapons they said Russia is transferring to pro-Moscow fighters in Ukraine.