Kharkiv in eastern Ukraine may be the next flashpoint in the Russia-Ukraine standoff

Russians call it Kharkov, the Ukrainians call it Kharkiv, and that's just one indication of what divides this city.

Kharkiv is the second largest city in Ukraine and it's only 25 miles from the border with Russia.

In recent days, it's been the scene of violent clashes between pro-Russian demonstrators and Ukrainian nationalists.

"The pro-Russia supporters — including some, I have to say, who were bused over the [Russian] border — attacked a government building which had been occupied by the pro-Kiev supporters. And they dragged these guys out and beat them," said PBS Frontline reporter James Jones, who was just in Kharkiv.

"The minority — certainly on the Russian side — is so extreme, so vocal and so violent. And if you’re standing in the town square and you’re surrounded by 5,000 of the Russian supporters, you think this city wants to be part of Russia. But actually, when you move away from the town center and you speak to people, a lot of them do actually support what happened in Kiev."

A violent confrontation between pro-Russian supporters and Ukrainian nationalists on Friday led to the deaths of two Russian demonstrators.

"They started attacking this building and the [Ukrainian] nationalists started shooting at the Russia supporters," Jones said. "And for the first time during all of this tension, shots were fired and two Russia supporters were apparently killed. And it really felt like the situation was escalating out of control."

Meanwhile, tensions remain high along the border between Russia and Ukraine. Jones says he saw a troop build-up on both sides.

"There are these 10,000 Russian troops on the border with some pretty serious weaponry," he says. "They're doing nighttime drills, so certainly the military want to give the impression that they are ready to invade at a moment’s notice." 

Jones says the Ukrainians are also sending in troops. "The Ukrainian military have given up on Crimea in the south, but they see the east as integral to their country. This would be a completely different order, if the Russians invade here."