In the first address to Congress by a NATO head, Jens Stoltenberg on Wednesday acknowledged serious divisions within the alliance and called for bigger defense budgets to cope with global challenges such as Russian assertiveness, the core reason NATO was created in Washington 70 years ago this week, TIME reported.

“We have to be frank,” Stoltenberg said before a joint meeting of Congress. “Questions are being asked on both sides of the Atlantic about the strength of our partnership. And, yes, there are differences.”

The NATO secretary general credited President Donald Trump with compelling allies to spend more on defense, without noting that Trump also has questioned the value of the alliance and suggested that some members are freeloaders.

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