US President Donald Trump has told NATO countries to increase their defence spending to four percent of their gross domestic product, higher than the group's goal of two percent, a White House official said on Wednesday.
The official said the president's remarks were not a formal proposal but came as he was urging leaders of the 29-member military alliance to increase their outlays on defence.
The US president has been openly critical of his NATO allies since becoming president in January 2017. Ahead of the summit being held in the Belgian capital, Brussels, Trump sent out a tweet about the funding of NATO.
Trump has repeatedly said the US was bearing an unfair burden because it spends many times more of its GDP on defence than other NATO countries.