"Trump's goal is to make the NATO summit a disaster — an international embarrassment that sows more discord inside Europe," Murphy, a Democrat from the US state of Connecticut, said in the message on Twitter.
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The NATO summit held in Brussels July 11-12 is off to a rocky start with Trump blasting European allies for not fulfilling their commitment to spend 2 percent of GDP to defense.
Trump also said that the United States protects Germany, which he characterized as a captive of Russia, and the country does not contribute enough to the alliance while at the same time buys Russian oil and gas.
Murphy said in his message that someone is benefiting from Trump’s behavior and attached a photo of Russian President Vladimir Putin.
Trump is scheduled to meet with Putin on July 16 in Helsinki, Finland.