Rep. Adam Kinzinger is facing a review from the Wisconsin National Guard after he publicly criticized Gov. Tony Evers over previously undisclosed troop withdrawals from the southern U.S. border with Mexico.

Kinzinger, an Illinois Republican who is part of a Madison, Wisconsin, unit, criticized Evers in tweets and a Fox News appearance earlier this week. The Wisconsin National Guard is looking into whether those comments may have violated the law.

The Milwaukee Journal Sentinel first reported this story. Wisconsin National Guard spokesman Capt. Joe Trovato told the Journal Sentinel that Kinzinger’s comments are being reviewed.

Kinzinger learned before leaving from his Air Guard mission in Tucson earlier this week that Evers was withdrawing his state’s Guard troops from the border. He questioned in a Monday tweet whether the decision was one “based solely on politics.”

Kinzinger sent his tweet hours before Evers officially issued an executive order calling the troops home in opposition of President Donald Trump’s claim that there is a national emergency on the southern border.

“Your guardsmen saved many lives and protected our country on this mission. Did you go visit them on the border to see for yourself? Or did you make your decision based solely on politics?” Kinzinger tweeted, asking Evers to “reconsider” the move to bring back the troops.

A spokeswoman for Kinzinger told the Journal Sentinel that he was within his rights to express a negative opinion about Evers’ decision, because he was off duty.

“The congressman is off-duty and has the right to exercise his freedom of speech as he so chooses, just as he has done when critical of the current president and the president before him,” spokeswoman Maura Gillespie said.

Wisconsin state and federal laws, and directives call for “any commissioned officer who uses contemptuous words against the president, the vice-president, members of Congress, the secretary of defense, the secretary of a military department, the secretary of homeland security, or the governor or legislature of the state of Wisconsin” to be punished.

Kinzinger is a reconnaissance pilot in the Air National Guard. He was deployed to the border two weeks ago.