Updated

Months after Russia annexed Crimea and stepped up support for separatists in eastern Ukraine, Europe and the United States are still searching for an effective way to persuade Russian President Vladimir Putin to change course.

Despite imposing targeted economic sanctions, and threatening tougher ones, the penalties have yet to alter what the west says is Moscow's growing backing for the rebels, including shelling of Ukrainian military targets from inside Russian territory and alleged plans to boost weapons supplies. That's happened even after the downing of a Malaysia Airlines plane galvanized support among reluctant Europeans for additional penalties.

Analysts say that with direct military options off the table, the U.S. and Europe may have to rely on sanctions aimed at pushing Russia into a recession.