"The administration has repeatedly urged Congress to pass comprehensive cybersecurity legislation to protect the American people from the growing danger of cyberthreats," Brennan said.
"Not only will military systems be targeted by tools that can cause physical destruction, but adversaries will increasingly attempt to hold our nation's core critical infrastructure at risk," Dempsey wrote. "Because the military relies on this infrastructure to defend the nation, we cannot afford to leave our electricity grid and transportation system vulnerable to attack."
Brennan is participating in a phone conference with reporters Wednesday afternoon along with U.S. Cyber Command head Gen. Keith Alexander and other administration officials to discuss cybersecurity legislation.
A cloture vote on Sen. Joe Lieberman's (I-Conn.) Cybersecurity Act is expected on Thursday, but it doesn't appear the measure will receive enough Republican support to move forward. Senate Republicans have voiced concern that Lieberman's measure would saddle companies that operate critical infrastructure with an additional set of regulations to follow.