NATO foreign ministers meet in Brussels Tuesday to talk about a stronger response to Russia's takeover of Ukraine's Crimea region.
This is the first senior-level NATO gathering since the crisis in Ukraine began last month.
So far, NATO has increased air patrols over the Baltics and the United States is planning more intense military exercises with Poland.
Diplomats say the ministers could decide to step up NATO military exercises or possibly set up permanent bases in Eastern Europe, closer to the Russian border.
Russia pulled back hundreds of troops from its border with Ukraine, Monday, but tens of thousands still remain.
U.S. Secretary of State John Kerry has told Russian Foreign Minister Sergei Lavrov that the Russian forces are creating a "climate of fear" inside Ukraine.