The terrorists used cell phones and other devices to communicate while the attacks were in progress, Kelly said Thursday. Witnesses in India also provided instant updates on the situation using cell phones, digital photos on the Internet, and Twitter -- communicating what they saw as it unfolded.
That can present a real danger to police and military units, who obviously don't want the attackers to know that they are entering a building through a particular door with a particular set of weapons.
It's unclear if authorities in New York could cut off attackers' cell service and other electronic communications without causing wider disruptions.
I hope they can.
The NYPD allows people to send them texts and photos for crime tips now. Texts and images could allow tipsters to gather intelligence during an attack. I would also argue that, since many people have done away entirely with landlines, intentional disruptions could cut New Yorkers off from communication with family members and friends during emergencies.
Millions of New Yorkers used phones -- landlines and cell phones -- to let out-of-town relatives and friends, as well as each other, know that they were OK after the Sept. 11, 2001, attacks. In many cases, those in the middle of the chaos relied on those watching the news outside of New York City for information to help them decide whether to flee the island of Manhattan by ferry, to head uptown, or to stay put.
As a New Yorker, I can't imagine an attack without the ability to let my family know I'm OK or the ability to exchange information and offers of assistance with friends scattered throughout Manhattan.