Fighting homegrown terrorism by monitoring internet communications is a civil liberties trade-off the US government must make to beef up national security, the nation's homeland security chief said.
As terrorists increasingly recruited US citizens, the government needed to balance Americans' civil rights and privacy with the need to keep people safe, Homeland Security Secretary Janet Napolitano said.
But finding that balance has become more complex as homegrown terrorists have used the internet to reach out to extremists abroad for inspiration and training.
Those contacts have spurred a recent rash of US-based terror plots and incidents.
"The First Amendment protects radical opinions, but we need the legal tools to do things like monitor the recruitment of terrorists via the internet," Napolitano told a gathering of the American Constitution Society for Law and Policy.
Napolitano's comments suggest an effort by the Obama administration to reach out to its more liberal, Democratic constituencies to assuage fears that terrorist worries will lead to the erosion of civil rights.
The administration has faced a number of civil liberties and privacy challenges in recent months as it has tried to increase airport security by adding full-body scanners, or track suspected terrorists traveling into the United States from other countries.
"Her speech is sign of the maturing of the administration on this issue," said Stewart Baker, former undersecretary for policy with the Department of Homeland Security.
"They now appreciate the risks and the trade-offs much more clearly than when they first arrived, and - to their credit - they've adjusted their preconceptions."
Underscoring her comments are a number of recent terror attacks over the past year in which legal US residents such as Times Square bombing suspect Faisal Shahzad and accused Fort Hood, Texas, shooter Major Nidal Hasan are believed to have been inspired by the internet postings of violent Islamic extremists.
And the fact that these are US citizens or legal residents raises many legal and constitutional questions.
Napolitano said it was wrong to believe that if security was embraced, liberty was sacrificed.
She added: "We can significantly advance security without having a deleterious impact on individual rights in most instances. At the same time, there are situations where trade-offs are inevitable."
As an example, she noted the struggle to use full-body scanners at airports caused worries that they would invade people's privacy.
Napolitano said officials had worked to institute restrictions on the scanners' use in order to minimise privacy concerns.
The scans can not be saved or stored on the machines by the operator, and Transportation Security Agency workers are not allwed to have phones or cameras able to capture the scan when near the machine.
