" Vladimir] Putin's aggression makes the possibility of a war in Europe between nuclear-armed adversaries frighteningly real," writes Kimberly Marten in a new Council Special Report on tensions between Russia and the North Atlantic Treaty Organization (NATO). She outlines how U.S. policymakers can deter Russian aggression with robust support for NATO, while reassuring Russia of NATO's defensive intentions through clear words and actions based in international law.

Marten, a professor of political science at Barnard College, Columbia University, and director of the Program on U.S.-Russia Relations at Columbia's Harriman Institute, lays out several scenarios that could lead to a dangerous confrontation, ranging from an inadvertent encounter between NATO and Russian military aircraft or ships to an intentional Russian land grab in Europe. The report, produced by the Center for Preventive Action at the Council on Foreign Relations, offers a plan for how the Donald J. Trump administration could work with Congress and NATO allies to lessen the chances of crisis escalation.