During a conference in Kyiv on the sidelines of the Yalta European Strategy, Ukraine's top diplomat Dmytro Kuleba says he regrets Western allies' slow progress on the creation of a special tribunal to prosecute Russian leaders, and on the transfer of frozen assets. "There is a lack of will to come to a conclusion," he says, opposing the G7's position on a hybrid tribunal that could allow Russian President Vladimir Putin or Foreign Minister Sergei Lavrov to uphold their immunity. "It's impossible to explain to Ukrainians that we could have a tribunal without Putin at the dock," says Ukraine's Prosecutor General Andriy Kostin, arguing for an international tribunal similar to Nuremberg's. IMAGES AND SOUNDBITES