WASHINGTON (AP) — As John Kerry prepares for a meeting tomorrow with Russia's foreign minister in London, he's issuing a warning to Russia that it will face a "very serious series" of steps from the U.S. and Europe if it annexes Ukraine's Crimea region.

Residents of Crimea vote Sunday on whether to join Russia -- but the U.S. and the European Union say the referendum violates Ukraine's constitution and international law. Still, Russia says it will respect the results.

Kerry told senators today that he hoped that "reason would prevail" but stressed there was no guarantee of that.


Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.