...Katherine Blakeley, a research fellow with the nonpartisan Center for Strategic and Budgetary Assessments in Washington, has crunched the numbers, and says the U.S. now accounts for 73 percent of all NATO defense spending. But part of that, Blakely says, has to do with America's superpower status and its unmatched military might. "The United States also has a very broad set of core global national interests that many of the European NATO countries don't necessarily share."
At a NATO summit in Wales in 2014, all 28 members of the alliance committed to a goal of spending at least 2 percent of their GDP on defense, as well as 20 percent of that on major equipment and weapons. So far only three countries have met that goal: the U.S., the U.K. and Poland. Two more, Greece and Estonia, spend 2 percent on defense, but not 20 percent on major systems.
So when NATO acts, as it did in Libya in 2011, it falls to the U.S. to do much of the grunt work. No other NATO nation has the necessary number of aircraft carriers, stealth bombers, GPS-guided cruise missiles, armed drones or spy satellites.
"There is an overreliance on the United States for those key enabling technologies, like air-to-air refueling, like [intelligence, surveillance and reconnaissance), like airborne [electronic warfare]," Blakeley said...