Covington & Burling has been hired by the Ukrainian government to represent the country in a lawsuit it has filed against Russia at the Hague-based International Court of Justice following Russia’s invasion of Ukraine.

Ukraine announced on Sunday that it would ask the U.N.’s highest court to find that Russia has no lawful basis to invade Ukraine under U.N. law. Russian President Vladimir Putin has claimed that the country’s invasion of Ukraine was justified to end the genocide it alleges Ukraine has committed in the Donbas region of eastern Ukraine.