The vice president of the United States is traveling this week in a region hotly contested by Washington and Moscow: the European borderlands. U.S.-Russian tensions intensified after the U.S. Congress passed new sanctions against Russia and Moscow responded by expelling U.S. diplomats and seizing diplomatic properties. With visits to Estonia, Georgia and Montenegro, the tour by U.S. Vice President Mike Pence is meant to reassure nervous allies on the front lines of the Russia-West standoff, while simultaneously highlighting Moscow's pressure points. As the United States and Russia ramp up their battle for influence in the borderlands, each of these countries and their broader regions will be key to shaping the trajectory of the standoff in the coming months. ...