With respect, I fear you may be confusing two different aspects of NATO funding. Member countries contribute in line with an agreed cost-sharing formula, based on Gross National Income. (GNI equals GDP plus income obtained in dividends, interest etc. from other countries.) Under that formula, the U.S. contributes 22.144 percent of the NATO budget, followed by Germany (14.65 percent), France (10.63 percent) and Britain (9.84 percent). The national contributions go towards NATO’s military costs, civilian costs and the NATO Security Investment Program (NSIP), which deals with investment in command and control systems etc.
What appears to be confusing many people, including your President (who really ought to know better), is this occurrence (and bear in mind the 2% is a guideline proposal - not a binding contract or agreement).
At the NATO summit four years ago, the allies declared their commitment to “reverse the trend of declining defense budgets, to make the most effective use of our funds and to further a more balanced sharing of costs and responsibilities.” To that end, the heads of state and government gathered in Wales that summer recommitted themselves to increasing defense spending in real terms and achieving the NATO
guideline to spend a minimum of 2 percent of each member’s Gross Domestic Product (GDP) on defense
by 2024.
Scaled to the scope of their interests and grand strategies, our NATO allies are generally committing about the same proportion of GDP to the defense of Europe as the United States.