Officially, there are no borders inside Ukraine.
But it doesn’t feel like that when you drive from its capital Kiev to the country’s industrial heartland in the east.
There is a series of checkpoints. At first, they are manned by Ukrainian army soldiers, who will search your car and check your travel documents.
If everything is in order, you proceed down a road where the trees have been shredded by gunfire, towards another fortified roadblock. The flags have changed colour, and the soldiers’ uniforms are not as regular.
You are now entering the People’s Republic of Donetsk.
In this place, the old statues of Lenin still stand, pictures of Putin hang from the walls in government offices and the currency you’ll need to buy food and clothes in the separatist economy is the Russian rouble.
The Republic is just three years old.
In 2014, a pro-Russian government was overthrown in Kiev, and war was sparked when pro-Russian separatists in the East rejected Ukraine’s new government.
That war has so far cost 10,000 lives, and a long stretch of its front line runs through the suburbs of Donetsk.
Lines of houses are pockmarked with bullet holes.
The airport – completed just five years ago when Ukraine hosted the European football championships – is a bombed out ruin.
Some people have made homes out of the old Cold War bomb shelter.
It’s not the only example of how Ukraine’s Soviet past is being used to serve the present.
On Victory Day columns of separatist fighters march through Donetsk to mark the defeat of Nazi Germany in the Second World War.
The crowds celebrate the foundation of their new state, and their independence from what they see as the ‘fascists’ in Ukraine’s new government.
The separatist state is totally dependent on Russian economic support and military backing.
It is only Moscow that recognises its makeshift borders and its freshly printed passports.
The rest of the world says the future of this place has to be settled by negotiation.
But the People’s Republic of Donetsk has one big ally. For now, that’s enough.
- For more on this story, watch On Assignment on ITV at 10:55pm on Wednesday, May 31