President Trump will urge NATO allies to fulfill critical defense spending commitments at a summit in Turkey this week.
The push follows assurances secured from member nations last year.
NATO's chief has called for that allies submit credible plans to reach spending goals.
U.S. officials have characterized heightening tensions as "growing pains."
Analysts reveal allies will obtain "report cards" to track their progress.
Various experts have warned of economic consequences if the demands are enforced fully.