Speaking in Doral, Florida, Trump said, "I think NATO's great. But it's got to be modernized. And countries that we're protecting have to pay what they're supposed to be paying."
It's a position that Trump has stated several times before
, saying he believes that the US is getting "ripped off"
and that some NATO members are getting an unfair "free ride."
on NATO payments earlier this month, when the alliance's members met to discuss a number of issues, including money.
NATO is based on the principle of collective defense: an attack against one or several of its members is considered as an attack against all. So far that has only been invoked once -- in response to the September 11 attacks.
To make the principle work, all countries are expected to chip in. NATO's official guidelines say member states should spend at least 2% of their gross domestic product on defense.
Of the 28 countries in the alliance, only five -- the US, Greece, Poland, Estonia and the UK -- meet the target. Many European members -- including big economies like France and Germany -- lag behind
. Germany spent 1.19% of its GDP on defense last year and France forked out 1.78%.
New spending data released this month
show the US shells out far more money on defense than any other nation on the planet. According to NATO statistics, the US spent an estimated $650 billion on defense last year. That's more than double the amount all the other 27 NATO countries spent between them, even though their combined GDP tops that of the US.
American military spending has always eclipsed other allies' budgets since NATO's founding in 1949. But the gap grew much wider when the US beefed up its spending after the 9/11 attacks. NATO admits it has an "over-reliance"
on the US for the provision of essential capabilities, including intelligence, surveillance and reconnaissance, air-to-air refueling, ballistic missile defense and airborne electronic warfare. The US also spends the highest proportion of its GDP on defense: 3.61%. The second biggest NATO spender in proportional terms is Greece, at 2.38%, according to NATO.
Iceland, which doesn't have its own army, spends just 0.1% of its GDP on defense, according to the Organization for Economic Cooperation and Development. Five other countries spend less than 1%, according to NATO's estimates for this year: Canada, Slovenia, Belgium, Spain and Luxembourg.
All member countries that fall below the threshold committed in 2014 to gradually ramp up military spending to reach the target within the next decade. Additionally, Democratic presidential nominee Hillary Clinton has also called on other NATO members to spend more on defense.
We can't verify whether the United States is getting "ripped off," but it's clear that most NATO member countries are not spending what the alliance's official guidelines require. Trump's statement is true.