As Iran rattles its sabers and Russia masses weapons in and around Ukraine, many are asking, “Where is the North Atlantic Treaty Organization?” What are its member states doing to bolster European stability and deter these new strategic threats?”

The alliance that once stood toe-to-toe with the communist bloc is silent and seems ill-prepared for today’s challenges. Not that long ago, NATO was the bastion of air-defense capability. With the end of the Cold War, however, members reduced their air-defense assets.

Nations have downsized their forces and are discussing further reductions. NATO’s robust training exercises have been reduced or eliminated, and the pursuit of weapons and equipment that could be integrated and can work together seems more a topic of discussion than an urgent need.

Yet post-Cold War Russia is emerging as a serious threat, and other nefarious world actors are demonstrating new capabilities. Moscow is developing advanced ballistic and cruise missiles and boasts a long-range strike capability. The Kremlin’s new doctrine characterizes NATO as a threat. Consider: NATO aircraft intercepted Russian military aircraft more than 400 times in 2014, as Russians probed into or near NATO airspace.

In addition, Iran has unveiled its unmanned aerial vehicle, declared itself the “world’s fourth-greatest missile power” and opened 2015 with a satellite launch of a rocket that could send a ballistic missile into Europe. Hamas, a Middle East terrorist organization like Islamic State, tested the Qasam rocket, fired more than 4,000 rockets into Israel in the 2014 conflict and flew its own unmanned aerial vehicles.

NATO’s air defense force, meanwhile, is stretched thin and limited in its ability to meet these new challenges. Most European nations have retired their short- to medium-range air defense systems. Germany’s Patriot force is about one-third the size at the end of the Cold War. The Netherlands ended its deployment to Turkey because its Patriot force is not large enough to sustain a third year of deployment. Spain backfilled the Dutch but only deployed a single Patriot unit for a mission that requires two.

The bulk of the U.S. Patriot force is forward stationed in the Pacific or deployed in Central Asia, leaving approximately 40 percent of it either recently home from a deployment or preparing for a deployment.

Fortunately, there are proven means to solve these challenges. First is greater integration of equipment. As General Frank Gorenc, the commander of U.S. Air Forces in Europe, recently explained, “the holy grail of interoperability is operating the same equipment.”

Two NATO allies, Poland and Turkey, are about to select new air and missile defense systems. Both began their acquisition process almost two years ago and both could acquire systems that would assure that all NATO weapons can work together in an integrated manner. The nations’ procurement leverages competition, and they have the opportunity to exploit the U.S. Army’s Patriot system. Stability in Eastern Europe and the value of interoperable systems are of such importance that a bipartisan group of 32 members of the U.S. Congress took the unusual step of writing to Polish Prime Minister Ewa Kopacz urging his country to acquire the Patriot system.

NATO once understood that interoperability, shared munitions and logistics, and combined training were critical to deterring aggression and — if deterrence failed — to mounting a robust response. The ability to quickly integrate an ally’s unit into the partners’ command, or share ammunition and repair parts, is essential in combat, particularly when dealing with low-density, mission-critical air defense systems. NATO also needs to resurrect its training and educational programs. This means creating an integrated air- and missile-defense training center like those the United States developed for Central Asia and the Pacific theaters. This center would complement a Patriot procurement decision and NATO’s Tactical Leadership Programme. A reinvigorated tactical program could, for example, enable the relatively new land-based version of the U.S. Navy’s SPY-1 radars with batteries of standard missiles, called Aegis Ashore, to operate with offshore Aegis ships stationed in the Mediterranean and also with NATO’s Patriot units. The synergies of this type of integrated network would put substance behind wishful rhetoric.

It is time for NATO to rejuvenate itself through focused leadership and a unified alliance that boasts educational and training programs underpinned with the most capable interoperability and shared weapon systems. Nothing less will enhance European stability or ensure its security.