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Story highlights

16 agencies, more than 100,000 people and $66 billion per year help fight the intelligence war

CNN was granted behind-the-scenes access

Watch a CNN Special Report, “Targeting Terror: Inside the Intelligence War,” Tuesday at 9 p.m. ET.

(CNN) —  

In the wake of the attacks in Paris, the world’s attention has refocused on terrorism, and in the U.S., conversations about national security have increased in both frequency and force.

The U.S. intelligence apparatus is vast, spanning some 16 agencies, with a staff of more than 100,000 people, a budget above $66 billion and a staggering array of operations, many of which are necessarily secretive.

CNN sought to shed some light on the United States’ many intelligence agencies and what they say they are doing to protect the country from threats around the globe. The overview included interviews with some of the nation’s top spies, and behind-the-scenes access never before granted to journalists. Here are five things we learned from inside the U.S. intelligence war:

1. The United States has satellites that “sense”

“We don’t have a presence physically in Syria,” Director of National Intelligence James Clapper admits. “When you’re thwarted in one direction with one particular discipline, you try to compensate for it in other ways.”

The United States compensates for its lack of human resources on the ground in Syria by trying to get the most out of its resources in space.

The National Reconnaissance Office has launched spy satellites to monitor activity the world over. But these satellites don’t just take pictures. Even from the void of space, they hear noise, sense heat and record vibrations.

“We used to play near tracks, railroad tracks, and you could feel the train coming before you could hear it. You could hear it before you could see it,” NRO Director Betty Sapp explained, comparing her childhood experience with the satellites.

This sensory data feeds into the NRO’s ground station in White Sands, New Mexico – what the NRO calls its “brain.” Then the NRO sends the information back out to those who need it in almost “real time,” according to Sapp.

“Whether it’s following signals or whether it’s tracing weapons, whether we’re making sure that the treaties that the U.S. has signed are actually being enforced, we contribute to all of those missions,” Sapp said.

Would the Iranian nuclear agreement fall into that category?

“We can contribute to that mission, yes,” said Sapp.

2. The U.S. intelligence community has built its own “virtual reality for surveillance”

National Geospatial-Intelligence Agency Director Robert Cardillo said the agency was able to build a model of the compound where Osama Bin-Laden was killed. The agency used satellite images taken of various angles of the compound – along with satellite images the agency had from before the compound even existed – to build a scale model of the now-demolished structures in Abbottabad, Pakistan.

However helpful that model from only a few years ago was, that kind of construction is a thing of the past. The NGA’s “immersion lab” offers virtual models, allowing the agency greater ability to display and understand details about an area. The agency can then share its models with people planning a mission – or soldiers executing one.

Marc Boysworth of the National Geospatial-Intelligence Agency even suggested giving information to soldiers on smart watches.

“They just may need to know danger from this direction and have it flash up on their Apple Watch,” Boysworth said.

3. The NSA hinted that it can break encryption

According to Clapper, people trying to avoid detection use couriers or go silent altogether. Asked if there was a way for the intelligence community to work past this, Clapper laughed.

“I mean, if they don’t communicate – no,” Clapper said.

One step removed from going silent and giving up on electronic communication is the practice of using encryption to cloak their conversations, what the NSA refers to as “going dark.”

“There is part of the world that’s dark to us. In other words, we can’t see,” Deputy Director of the NSA Richard Ledgett said.

In the rest of the world, end-to-end encryption can secure communications from the sender to the receiver, which means that theoretically, no one can intercept the information. Many technology companies and privacy advocates have embraced encryption, to the chagrin of law enforcement. Following the attacks in Paris, the debate over the strength of encryption has bubbled up again. FBI Director James Comey renewed his calls for backdoor access to encrypted communications after reports the Paris attackers had encryption apps on their phones.

The debate about encryption aside, the privacy technology may not be a total roadblock for the U.S. intelligence community.

Asked if the NSA had a way around encryption, Ledgett said, “So that’s a really difficult question to answer. Sometimes there is. Sometimes with a lot of work there is.”

4. The U.S. has an ISIS-related investigation in every state

The United States has 900 investigations pending against suspected operatives it says ISIS inspired. There is at least one investigation in every state.

ISIS recruits from the United States have typically been young and active online, but they have not fit one ethnic or geographic profile. Most ISIS recruitment stories seem to follow a pattern, with ISIS recruiters trying to entice young people from the internet to come their corner of the world. According to Peter Bergen, a CNN national security analyst, ISIS sent one 23 year-old woman chocolates and books. The recruiters talked to her online for thousands of hours.

And once ISIS recruiters feel comfortable, they offer potential recruits advice and even a “travel guide” to get to Syria.

“It’s basically everything you need to know about how to get into ISIS territory,” Bergen said.

5. Foreign actors have the capability to take down U.S. infrastructure

Electricity, water, transportation, finance – virtually all the things underpinning daily life in the United States – are vulnerable to cyber attacks.

“We are in a battle, if not an actual war, in cyberspace,” Ledgett said.

The deputy director of the NSA went on to list China, Russia, Iran and North Korea, as well as non-state actors like criminals in Eastern Europe, as perpetrators of cyber attacks against the United States.

Ledgett claimed the NSA’s Cyber Command views “hundreds of thousands” of attacks every day.

The U.S. believes Russia breached an unclassified White House network and that China was behind a massive hack into the Office of Personnel Management.

CNN’s Jim Sciutto contributed to this report.