Ukrainian President Volodymyr Zelensky has issued a stark warning that Russian leader Vladimir Putin could be prepared to strike NATO within the next five years. He urged the alliance to expedite plans to bolster defense spending.

The Ukrainian president said Russian President Vladimir Putin could attack a NATO country within five years to test the alliance.

The alliance’s summit will minimize references to either Russia or Ukraine to avoid antagonizing the U.S. president who has sided with the aggressor.