President Barack Obama embarks on a four-day trip to Europe this week. He leaves Washington Monday night for stops in Poland, Belgium and France.
  
 The U.S. leader's trip to Europe comes at a time when Russia has made threatening moves on Ukraine. There is also deep uncertainty about Ukraine President-elect Petro Poroshenko's ability to stabilize his country. Obama will meet with Poroshenko in Poland. President Obama will confer with U.S. allies Wednesday and Thursday in Brussels at a Group of Seven meeting that was quickly arranged after leaders decided to boycott a meeting Russia had been scheduled to host this week.
  
 In France on Friday, Obama will speak in Normandy at Omaha Beach for a ceremony marking the 70th anniversary of the allied D-Day invasion against Nazi forces in World War II.