(CNN) Republican Sen. Lindsey Graham called President Donald Trump's decision to immediately withdraw US troops from Syria a "disaster" and "a stain on the honor of the United States."

In a speech on the Senate floor Wednesday night, Graham, one of Trump's closest allies in Congress, called the move "disastrous to our own national security" and a decision that was made "against sound military advice." Graham said this decision would make Americans around the world and here at home "more at risk, not less."

The South Carolina congressman said he was shocked by the decision and characterized the move as a betrayal to our allies in the region

"We have been dishonorable. This is a stain on the honor of the United States," Graham said.

Graham, who said he just got back from a trip to Afghanistan, said: "Having been in the military for quite a while, I'm very aware of the sacrifices required to go overseas and serve in Iraq, Syria and Afghanistan."

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