WASHINGTON — The military’s top cyber-security fighter said Tuesday that network threats to the nation are on the rise, calling on lawmakers to pass legislation that helps establish lines of authority in cyberwarfare.

“When you look at the strategic landscape from our perspective, it’s only getting worse,” said Gen. Keith Alexander, Director of the National Security Agency and head of the U.S. Cyber Command, while testifying before the Senate Armed Services Committee. Since 2010 Alexander has headed Cyber Command, which protects the government’s information networks.

In response to a rash of cyber thefts from American companies and government agencies by foreign hackers, the four-star Army general said military commanders will soon be able to deploy teams of cyber security experts more efficiently to combat the network intruders.

“The teams are analogous to battalions in the Army and Marines, or squadrons in the Navy and Air Force,” said Alexander, who also heads the National Security Agency.

Lawmakers must define a framework for defense, he said, since the line between a cyberattack and an act of war is blurring. In Alexander’s view, network intrusions on the nation’s critical infrastructure, such as electric grids, could be seen as acts of war.

With 140 cyberattacks on Wall Street in the last six months, specific duties must be defined for the Defense Department, FBI and Department of Homeland Security, Alexander said, because they lack cyber jurisdictions.

“It takes a team to operate in cyberspace, but at times I think in talking about the team approach, we’re not clear on who’s in charge when,” he said. “These agencies need to be able to share classified information in real time.”

A month after President Barack Obama signed an executive order designed to bolster network security, Armed Services Chairman Sen. Carl Levin, D-Mich., said the Defense Department will define “rules of engagement” in cyberwarfare.

“The fact that these foundational policy frameworks and planning actions are just now taking shape serves as a stark illustration of how immature and complex this warfare domain remains,” Levin said.

Alexander said that while his agency, the cyber command, has doubled efforts to combat cybertheft of trade secrets and intellectual property by China, those efforts could be limited by cuts of roughly $50 billion in the Defense Department budget  as a result of sequestration.

“There will be impacts that we can’t predict,” Alexander said, adding that unpaid furloughs as a result of sequester cuts could deter top cyber-security experts from working for the government.