US President Donald Trump has complained again about the defence expenditure of the North Atlantic Treaty Organization (NATO) members, one day ahead of his departure for a NATO summit scheduled in Brussels, Belgium.
"The US is spending far more on NATO than any other country. This is not fair, nor is it acceptable," tweeted Trump tweeted on Monday, Xinhua news agency reported.
"While these countries have been increasing their contributions since I took office, they must do much more," Trump added.
The US President has long been scolding the NATO countries which have not met the 2-per cent-of-GDP benchmark on military spending. It has also been seen as a key topic for the upcoming NATO summit slated for July 11-12.
"NATO benefits Europe far more than it does the US," Trump claimed.
NATO's European allies have spent more on defence for a second consecutive year in 2017 but the majority of them still failed to meet the target of spending 2 per cent of their gross domestic product on defence.
Eight NATO allies will reach the 2 per cent benchmark by the end of this year, and 15 are on track to spend 2 per cent by 2024, according to a statement released by the White House recently.
In late May, Trump threatened that NATO member states who have not met their financial obligations regarding defence will be "dealt with", and specifically called upon Germany to fulfill its obligation.