BRUSSELS (Reuters) - NATO head Mark Rutte warned the U.S.-led transatlantic alliance on Thursday that it was not ready for the threats it would face from Russia in the coming years and called for a shift to a wartime mindset - with much higher defence spending.

Rutte said NATO members had spent more than 3% of GDP on defence during the Cold War, and future spending would have to be much higher than the current alliance target of 2%.

"Russia is preparing for long-term confrontation, with Ukraine and with us," Rutte said in a speech in Brussels.

"We are not ready for what is coming our way in four to five years," the NATO secretary-general said, adding: "It is time to shift to a wartime mindset, and turbocharge our defence production and defence spending."

(Reporting by Lili Bayer, Editing by Charlotte Van Campenhout and Kevin Liffey)