Nervously eyeing Russian naval maneuvers and military flights near their borders, the three ex-Soviet Baltic states fear they may emerge as the next geopolitical flash point after Ukraine in a confrontation that could test their cherished Western ties.

With U.S. President Barack Obama heading to Estonia on Wednesday on a visit designed to underline Washington's solidarity with the Baltic states ahead of a NATO summit in Wales, the three tiny republics are renewing calls for troops on the ground and military help.

In their comments on the Ukraine crisis, Estonia, Latvia and Lithuania are more hawkish than their Western partners. Anchored in NATO, unlike Ukraine, they have far less cause to fear a full-blown Russian military invasion, but they worry about cyberattacks and other more stealthy forms of aggression.