The eastern Ukrainian port city of Mariupol is just 30 kilometers from the Russian border, and was previously controlled by the Donetsk People’s Republic. The Ukrainian military has done its best to fortify the industrial hub after winning it back, but many believe that the pro-Russia separatists plan to seize control of it once again. In this dispatch from Ukraine, VICE News correspondent Simon Ostrovsky discovers the strategic significance of Mariupol in the conflict in eastern Ukraine, and learns how the city is preparing for the possibility of falling under siege from pro-Russia separatist forces.