Massive Security The U.S. Secret Service and F.B.I. have been in Chicago coordinating security efforts for at least the last two weeks.
Air Force F-16 jets are on alert to enforce flight restrictions over Chicago, and the U.S. Coast Guard is patrolling the waters of Lake Michigan with heavily armed vessels.
The Illinois National Guard and Illinois State Police will help shuttle motorcades to and from O'Hare Airport.
Sharp-shooters will be posted along the city's famed Michigan Avenue.
Bomb-sniffing dogs are on public transportation, and teams of officers on foot, and on bicycles, are scattered across the downtown area.
At a secret location in the suburbs outside Chicago, a Multi-Agency Communications Center—dubbed MACC-- has been created. Representatives from 43 federal, state, and local agencies will be in the same room to share real-time security information with each other.
Roger Goodes with the United States Secret Service says streamlined communication will be key should an emergency strike.
"For us in this room, we fear nothing. We think we are prepared to handle anything that comes up."
The Chicago Police Department is spearheading security on the ground.
All of the department's nearly 13,000 officers will be on the clock this weekend. Also, police officers from Milwaukee and Philadelphia have been called in for back-up.
Police Superintendent Garry Mccarthy says he wants to protect demonstrators' first amendment rights to protest, but safety will be paramount.
Police will be using high-tech countermeasures such as "sound cannons"—a device that can emit ear splitting sounds and messages to large crowds-- should protests threaten to get out of hand.
Authorities have also been consulting with police in Seattle, a city scarred after a World Trade Organization meeting in 1999 led to several days of violence there.
Superintendent Mccarthy is also trying a new approach. In an effort to not incite protestors, many officers will be in their everyday uniforms. Officers in full riot gear will be standing by and deployed when necessary.
Security expert Jeff Cramer, with Kroll Advisory Solutions, believes the months of training officers have undergone will go a long way to keep protests peaceful.
"The lessons that they have learned and the discretion of the police officers on the scene, that's what it comes down to. It's the police officer on the scene who is confronted with a protester, what does he or she do? And it's that discretion and training, that's what's going to determine how this weekend goes."
The security measures extend online as well, where cyber-police are working to block hackers before they strike. Authorities also say they are closely following Twitter and Facebook messages posted by protest groups, in hopes of stymieing off any threats before they become a reality.
The NATO Summit is supposed to bring almost $130 million in revenue to city coffers.
But for some business owners the conference will cost them money.
Fearing that protests could lead to riots and looting, some businesses have decided to keep their doors closed this weekend.
Rosa Yamada, who owns Designs by Rosa, a flower shop in downtown Chicago, will not be opening this weekend. The month of May is the middle of flower-selling season—peak time for graduations, weddings, and other ceremonies where flowers are a must.
Choosing to close this weekend was a tough decision, likely to cost her hundreds of dollars in business. Yamada fears street closures, and the uncertainty surrounding protests, will keep customers from coming in.
"In the 20 years that I've been in business, this will be the first Saturday—for the very first time—that we will be closing. I'm concerned for things going crazy."
Many businesses, including 22 Starbucks stores, have installed plastic film overlays to keep storefront windows from shattering.