In July, after the NATO summit in Brussels, US President Donald Trump tweeted that "the United States is spending far more on NATO than any other country. This is not fair, nor is it acceptable." But, is the US spending more on NATO than other members? And, if so, is the US spending level unfair relative to that which the US—and the other 28 members—have agreed? Let's look at the data.

Measure 1: Defense Expenditures. In 2018,* the US will spend an estimated $706 billion on defense globally. The US defense budget represents US priorities and spending globally and not money spent for or on behalf of NATO or for the mutual defense of the alliance members. NATO-Europe is expected to spend $286 billion on defense in 2018.

Personnel expenditures constitute the largest single category of anticipated US defense expenditures in 2018 (42.5%)—which includes pensions paid to retirees—followed by equipment and related R&D (26.8%).

Defense infrastructure makes up only 1.3 percent of total US defense expenditures in 2018, down from 3.1 percent 2011.

Measure 2: Share of GDP. In 2014, In 2014, NATO members agreed as a signal of political will and validation of the alliance to increase defense expenditures to at least two percent of GDP by 2024. According to 2018 estimates, by this measure a few countries have already met the commitment while other countries are still working up to the 2024 standard: the US, 3.5 percent; Greece, 2.3 percent; Estonia, 2.1 percent, and the UK, 2.1 percent.