WASHINGTON -- President Barack Obama’s complex relationship with Europe faces new tests during his overseas trip this coming week.

He’ll try to persuade allied leaders to hold firm in efforts to punish Russia for its move against Ukraine.

The deepening dispute between East and West is expected to dominate the four-country trip. He leaves Washington late Sunday.

The trip, which includes a stop in Saudi Arabia, was long-planned. But it now provides the U.S. and Europe a well-timed opportunity to present a united front against Russian President Vladimir Putin.

Behind the scenes, Obama will be gauging how far the still economically shaky European Union is willing to go in punishing Russia, its largest trading partner.

He’ll also be confronted with other European frustrations with the U.S. that are bubbling below the surface.