WARSAW, July 4 -- Donald Tusk told reporters on Friday that Russia could strike a NATO member within "months rather than years," making public what Polish officials said had been a persistent stream of American intelligence warnings about a potential Russian provocation on NATO's eastern flank. The coming weeks, the Polish prime minister said, "may prove critical."

The statement came not from an anonymous intelligence briefing but from Tusk himself, at a press conference in Warsaw, hours before his delegation's departure for next week's NATO summit in Ankara. That context matters. Governments typically keep threat assessments private until forced to speak, and Poland has been receiving these warnings, Tusk indicated, for some time. "For ...