Updated

Losing the country's ability to monitor Americans' conversations with people overseas would take away half of the tools the U.S. uses to fight terrorism, Director of National Intelligence J. Michael McConnell told senators Monday.

"If we lose FISA, we will lose, in my estimate, 50 percent of our ability to track, understand and know about these terrorists, what they're doing to train, what they're doing to recruit, and what they're doing to try to get into this country," McConnell said, referring to the Foreign Intelligence Surveillance Act.

McConnell also credited the law as critical in last week's arrests in Germany of suspected terrorists. The 1978 law — updated last month by Congress — allows the U.S. to monitor conversations that take place overseas.

The FISA legislation that passed last month is a temporary fix, McConnell said. Civil liberties advocates and some leading congressional Democrats think the updated law gives the intelligence community too much surveillance power, and want to revisit it to add more limits.

"Some are of the belief that this community is spying on Americans, doing data-mining and so on. Simply not true," McConnell said.