US President Donald Trump has threatened to take action on trade with countries that he says are are not contributing enough to NATO Following his trip to London for a NATO meeting, Trump said Thursday the US was “paying far more than anybody else,” but added, some countries were failing to pay their fair share.

“A lot of countries are close and getting closer.  And some are really not close.  And we may do things having to do with trade.  It’s not fair that they get US protection and they’re not putting up their money,” Trump said.

“It’s not fair that they get US protection and they’re not putting up their money,” he added in remarks posted on the White House website.

This comes after Trump and his French counterpart Emmanuel Macron clashed over the future of NATO on Tuesday before the summit held to celebrate the 70th anniversary of the Western military alliance.

Relationships between Trump and Macron were already strained over a trade dispute, and after the French president called NATO "brain dead" last month because, in his opinion, the US commitment to the alliance was fading.

Trump hit back on Tuesday by saying the French leader had been "very disrespectful", adding Paris had "a very high unemployment rate" and "nobody needs NATO more than France".

Trump has been a fierce NATO critic, mostly accusing other military alliance members of not paying their “fair share.”