Russian President Vladimir Putin’s prospective invasion of Ukraine will create a major refugee crisis for the European Union, according to a senior Ukrainian defense official who cautioned European officials not to underestimate the scope of the looming conflict.

“It will be a lot of refugees,” Ukrainian Defense Minister Oleksii Reznikov said in a Wednesday interview with the BBC. “It will be a disaster for Europe because this war is not only [in the] east of Ukraine. This war is going in [the] east of Europe. I am seriously saying.”