The rare visit by a senior U.S. official marks another step in the U.S. campaign to make Europe and Canada spend more on their own defence. Washington also wants to probe their loyalty after several NATO countries curbed access to their airspace and to American bases linked to the U.S.-Israeli war on Iran, reports Victor Jack in Politico.

Overall, the review “will encourage, enable, and impel a transition to a more durable and powerful European-led conventional defence of the continent,” Colby told NATO’s 32 ambassadors, according to his published remarks.

Some NATO allies have bridled at the approach. Earlier this month the U.S. sent out a questionnaire, according to two European defence officials, asking allies to detail their views on subjects ranging from defence spending to U.S. foreign policy.

It’s a “scary exercise,” said a NATO diplomat, describing the survey as an attempt to get allies to “pledge their allegiance to the king.”