A challenge is expected at the upcoming NATO summit, with US President Donald Trump seeking more from the alliance. The NATO secretary-general has been working to maintain US involvement in the alliance.

The issue initially centered on defense spending, with Trump criticizing allies for not allocating enough of their budgets to defense. However, this concern was addressed at last year's summit, where allies committed to invest in defense.

Further details about the current situation and the upcoming summit are available from the source, including the shift in focus from spending to military capabilities.