Europe could not defend itself without American military backing, a warning that lands badly for NATO allies still spending little on defense.

• Without U.S. help, a war in Europe would be over in days, according to a blunt Polish assessment of the continent's readiness.
• Most European countries are seen as unwilling to fight or pay for their own defense.
• Poland now spends well above NATO's 2% target, closer to four percent, and is held up as the exception.
• Poland links its ability to spend more to keeping out mass migration, which it blames for much of Europe's wider trouble.

Outlook: Pressure on European governments to raise defense spending will keep growing as long as Washington questions the value it gets from NATO.