Rep. Mike Waltz (R-FL) stressed the importance of the United States properly responding to cyberattacks, contending that the nation’s foreign adversaries are not “getting the message.”

Waltz’s comment was in reference to the cyberhack the Library of Congress’s email systems underwent this year. The FBI is investigating the scale of the attack, Fox News has confirmed. The Florida congressman, whom President-elect Donald Trump named his national security adviser, warned that the cyberattack could open the door to other parts of the U.S. government being hacked and said the U.S. cannot “keep playing 100% defense.”