NATO has tweaked and tested its air defense systems to provide coordinated sensor (mainly radar) and control capabilities to support anti-missile missiles. The United States and several other nations have anti-aircraft missile systems that can also knock down ballistic missiles (mainly short range ones.) Now, the NATO air defense system can have additional anti-missile systems added, with the entire system able to coordinate defense against missile attack. The ultimate goal is to install American anti-missile systems capable of stopping longer range ballistic missiles, like those from Iran. This is expected to happen before the end of the decade, or sooner, if Iran becomes more threatening to European NATO members.