In February, Trump said that a leader of an unspecified NATO member state asked him whether the US would protect NATO allies from a Russian attack if they do not meet their defense spending obligations. Trump responded that the US would not defend delinquent allies and would encourage Russia to “do whatever the hell they want,” adding that NATO members have to pay more into the alliance. Trump also expressed dissatisfaction with the work of the alliance and threatened to withdraw the US from NATO if European partners do not bear greater financial responsibility for their own security.

One European diplomat told the newspaper that Trump’s comments about US membership in NATO were “of course” a “concern.”

“Nobody knows what he’s going to do next,” the diplomat was quoted as saying by the newspaper.

A third diplomat noted that uncertainty over US membership in NATO would make European countries “think in our own capitals more about the defense planning – is it adequate or not,” the newspaper reported.