WASHINGTON (AP) — Since the Cold War ended two decades ago, Washington has considered Moscow mostly as an unreliable ally — and, at times, a stubborn adversary, in efforts to boost the global economy, curb weapons proliferation and calm other nations in tumult. At the same time, Russia’s role as a key participant in international efforts to solve global crises gives it the ability to hurt the U.S. if it decides to be uncooperative or openly obstructive.

Some of the tensions can be chalked up to pure competition. The range and scope of Russia’s natural resources are second only to the U.S. and it is the world’s largest natural-gas exporter. Moscow has stepped up diplomatic ties with China and, more recently, across the Mideast to provide a counterpoint to Western influences in countries the U.S. is trying to win over. This week, President Barack Obama downplayed Russia as a “regional power” — despite Russian President Vladimir Putin’s clear desire to restore his country to the global superpower status it held as the core of the Soviet Union.