President Trump will push NATO allies to fulfill key defense spending commitments at a summit in Turkey this week.
The pressure follows promises secured from member nations last year.
NATO's chief has demanded that allies submit robust plans to reach spending benchmarks.
U.S. officials have described heightening tensions as "growing pains."
Analysts show allies will get "report cards" to track their progress.
Certain analysts have cautioned of financial consequences if the demands are implemented fully.