President Trump will press NATO allies to fulfill critical defense spending commitments at a summit in Turkey this week.
The coercion follows assurances secured from member nations last year.
NATO's chief has demanded that allies submit plausible plans to reach spending goals.
U.S. officials have described heightening tensions as "growing pains."
Reports indicate allies will obtain "report cards" to track their progress.
Various experts have cautioned of economic consequences if the demands are applied fully.