The United States has asked European nations what they can contribute in terms of security guarantees for Ukraine, Finland's president said on Saturday, amid escalating diplomatic efforts to find ways to end the three-year war with Russia.

Earlier, four European sources said the U.S. had sent a document asking questions that included possible future troop contributions, with two of the sources adding that it had been sent earlier this week.

"The Americans have provided Europeans with the questionnaire on what would be possible," Finnish President Alexander Stubb told Reuters at the Munich Security Conference.
"This will force Europeans to think, then it's up to the Europeans to decide whether they actually answer the questionnaire, or whether they answer it together."