Washington (CNN) President Donald Trump's nominee for Assistant Secretary of Defense for Health Affairs, Dr. Dean Winslow, said Tuesday it is "insane" that a civilian can buy a semi-automatic weapon like the gun that Devin Kelley used in the Texas church shooting.

Winslow made the comments in his confirmation hearing with the Senate Armed Services Committee.

"I may get in trouble with other members of the committee, just say how insane it is that in the United States of America a civilian can go out and buy a semi-automatic assault rifle like an AR-15, which apparently was the weapon that was used," Winslow said.

Law enforcement have said Kelley used Ruger AR-556, which is a variant of an AR-15.

The Pentagon declined to comment on Winslow's remarks.

Read More