John Bolton backs up John Kelly in Twitter fight with Donald Trump

Former national security adviser John Bolton backed up former White House chief of staff John Kelly in a tweet on Thursday.

Thursday morning, Kelly spoke out in support of Lt. Col. Alexander Vindman, which earned him the ire of President Donald Trump.

Bolton responded by saying that he knows Kelly to be "an honorable man."

"John and I have disagreed at times, as is commonplace at senior government levels, but he has always served his country faithfully. Conservatives especially have a responsibility to reject baseless attacks upon him," he tweeted.

Vindman responded to Trump's attacks in a statement from his attorney.