Lt. Col. Alexander Vindman, the National Security Council Ukraine director who said he was disturbed by President Trump’s phone call with Ukrainian President Volodymyr Zelensky, testified in Tuesday morning’s Democratic-led impeachment hearing.

Vindman, who was criticized by some for wearing his military uniform for his closed-door testimony in late October, again appeared in full military uniform as he faced a packed room and an array of cameras alongside Vice President Mike Pence’s adviser Jennifer Williams.