Standoff at Airport in Eastern Ukraine Poses Challenge for New President

UPDATED: 9:25 a.m. ET

DONETSK, Ukraine — Clashes broke out on Monday at the airport in restive Donetsk when pro-Russian separatists stormed the terminal and demanded the exit of Ukrainian troops, presenting the first immediate challenge for Ukraine's president-elect, Petro Poroshenko, the day after his election.

The fighting came as both Poroshenko and Russia's foreign minister said they were open to talks, but with Poroshenko vowing to continue operations against the separatists in his country's east and Russia warning that the military action must stop.