President Trump has not specifically authorized the U.S. to disrupt Russian cyber operations or head off potential attacks on the 2018 elections, the head of U.S. Cyber Command said.

Adm. Mike Rogers, who is also National Security Agency director, warned the Senate Armed Services Committee that the country is not doing enough to counter the Russian threat but said he would need direction from the president or Defense Secretary Jim Mattis to target the foreign operations.

Democrats on the committee were angered that the Pentagon’s cyber force had not been tasked to take on the Russia operations, which U.S. intelligence officials found meddled in the 2016 presidential election and will likely try to disrupt the midterms this fall.

“Why the hell not? What’s it going to take?” Sen. Claire McCaskill, D-Mo., said. “I want somebody to sit in that chair and say to the United States of America we’ve got this and until we have that moment, Russia is winning and that is disgusting.”

Three Armed Services Democrats wrote to Mattis this month asking that he take action against the Russians, who have hacked the party’s emails and used an army of bots in an attempt to stoke U.S. political divisions online.

“One of the things that we asked is that the national mission teams, which are part of the U.S. Cyber Command’s cyber mission, should be ordered to prepare to engage Russian cyber operators and disrupt their activities as they conduct clandestine influence operations against our forthcoming elections,” said Sen. Bill Nelson, D-Fla., who sent the letter with Sens. Jeanne Shaheen, D-N.H., and Richard Blumenthal, D-Conn.

Rogers, who was appointed by former President Barack Obama and is set to retire this spring, said Russia is attempting to undermine U.S. institutions and has not been deterred so far.

“My concern is I believe that President [Vladimir] Putin has clearly come to the conclusion there is little price to pay here and that therefore [he] can continue,” Rogers told the Senate panel. “Everything that as both director of NSA and what I see on the Cyber Command side leads me to believe that if we don’t change the dynamic here he is going to continue and 2016 won’t be viewed as something isolated. This is something that will be sustained over time.”

Rogers said the U.S. has not engaged in the same type of cyber operations being waged by Moscow, but he pushed back at Democrats' claims that the administration is “sitting back and waiting” to see what happens.

“Based on the authority that I have as a commander I have directed the national mission force to begin some specific work. I’d rather not publicly go into that, using the authorities that I retain as a commander of this mission,” he said.