A counterterrorism expert says that Iranian sleeper cells may be hiding "in plain sight," waiting to strike rural areas in America.

Following strikes by the U.S. military on several Iranian nuclear sites on June 22, the Department of Homeland Security (DHS) issued a National Terrorism Advisory System Bulletin, stating there's a heightened risk for Iranian-backed or domestic terrorism.

"The likelihood of violent extremists in the Homeland independently mobilizing to violence in response to the conflict would likely increase if Iranian leadership issued a religious ruling calling for retaliatory violence against targets in the Homeland," stated the bulletin. "Iran also has a long-standing commitment to target US Government officials it views as responsible for the death of an Iranian military commander killed in January 2020."

Jonathan Gilliam former FBI special agent who has worked on terrorism task forces, told Fox News Digital that these terror cells might be in our backyard.

COLLEGE CAMPUSES COULD BE GROUND ZERO FOR IRANIAN SLEEPER CELLS PLOTTING TO HARM AMERICANS, EXPERTS WARN

"Where these sleeper cells may be is in plain sight," Gilliam said. "And that's the real terrifying part of this is that putting people in place, as we've seen over the past four years, everyone's scrambling because certain amounts of people could come in here and get in here."

Gilliam said the Biden administration's border policies enabled Iranian illegal immigrants to come into the U.S. with impunity, creating the conditions for sleeper cells to exist.

"They could even go to the border and say they [want to] seek asylum, and the Biden administration, instead of putting them into DHS housing or ICE housing and holding them there so they could have their first appearance. To be vetted and whether or not they get asylum," he said of Iranian illegal immigrants.

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Following the U.S. attack on Iran's nuclear facilities, U.S. Immigration and Customs Enforcement (ICE) has tamped up enforcement efforts targeted at Iranian illegal immigrants.

Since June 18, over 130 Iranian nationals have been arrested, multiple federal sources told Fox News, adding that 670 Iranians are in ICE custody.

Gilliam said that these sleeper cells could be targeting America's rural areas since they're "not well protected."

"There is a possibility that sleeper cells could target more rural states instead of a large city. In fact, considering the evolution of attacks by fundamental Islamic attackers we’ve seen in Israel on October 7th, 2023 and in India this year, it is possible that a similar attack could happen at a rural, outdoor entertainment venue or populated vacation spot," Gilliam said.

Fox News' Bill Melugin contributed to this report.

There can be a lot of harmful substances that live in the air we breathe. Pet hair, dust and airborne bacteria, just to name a few. Investing in an air purifier for your home can help you breathe better and reduce allergies. Purifiers cycle clean air into your home while trapping toxins. 

Amazon now has Prime Day deals that run through July 11 on a variety of air purifier brands. Just make sure you're an Amazon Prime member before you start shopping. 

Our list has air purifier options for small rooms, large rooms, pet owners and units with scent diffusers. 

Want to clear out the air in your entire home? There are air purifiers that are up to the task. They're typically more expensive and larger, but can be well worth the investment. 

Original price: $189.99

The Levoit air purifier is a high-end cleaner that can be used in spaces of up to 1,878 square feet and can quickly purify air thanks to the U-shaped air inlet that helps ensure pet fur and hair don’t cause clogs. You can buy it on Amazon or visit Levoit's site for more air purifier options.

Original price: $189.99

The well-designed Coway Airmega Mighty air purifier doesn’t take up a lot of space, but can clean the air in rooms up to 874 square feet in 30 minutes. The air purifier makes automatic adjustments to purify the air in your space more effectively and efficiently. Coway's site offers a wide variety of high-tech air purifiers you can check out.

Original price: $339

A Coway Airmega 350 can filter the air in spaces of up to 2,640 square feet in just 60 minutes. The advanced 3-in-1 filtration system eliminates pollen, pollutants and allergens that cause seasonal allergies. A built-in sensor tracks the air quality in real time and can adjust the fan speed as needed. 

Original price: $999

The Coway Airmega ProX is a powerhouse that can filter the air in your entire house. The air purifier's HyperCaptive filtration system uses a true HEPA filter that captures up to 99.9% of particles in the air. Choose between three different fan speeds, or choose auto mode to automatically optimize the fan speed. When no air pollution is detected for 30 minutes, the device automatically shuts off. 

Pets in the home can irritate your allergies. There are more powerful air purifier models on the market that can help keep pet hair out of the air.

Original price: $219.99

Honeywell's AllergenPlus HEPA air purifier has three cleaning levels, including a Turbo Clean mode that helps get rid of pet dander, dirt, pollen and smoke. You can clean the air in rooms of up to 1,500 square feet in just 60 minutes. For smaller rooms of up to 310 square feet, the air can be fully purified in just over 12 minutes. 

Original price: $129.99

The Pure Enrichment air purifier has a HEPA air filter and a UV-C light to help eliminate up to 99.9% of viruses and bacteria and 99.97% of dust and allergens. The device is designed for rooms of about 300 square feet and comes with three fan speeds and three automatic timer settings for two, four or eight hours. 

Original price: $699.99

Homes with lots of pets need a powerful air purifier and the Blueair Classic Pro CP7i can handle the job. It's quiet and rapidly purifies areas of up to 1,413 square feet in just 30 minutes. The dual fan and filter design quickly draws in pet hair, dirt and allergens while pushing out clean air. You don't have to worry about this filter significantly raising your electric bill, since it automatically shuts off once it no longer detects allergens. 

Smaller rooms don't require large air purifiers. If you want a purifier for your home office, or the bathroom where you keep a litter box, one of these air purifiers will work perfectly fine. 

Original price: $49.99

The sleek-looking Aroeve air purifier has 360-degree air inlets to quietly filter out smoke, pollen, hair and more. It recycles the air through the room every hour and works best in areas of up to 287 square feet.

Original price: $61.99

The Fulminare air purifier is designed with 360 degrees of air intake, drawing in dust from every corner of the room. It’s well-suited for rooms up to 215 square feet. You can also score a good deal on a Fulminare air purifier online at Sears.

Adding a nice scent to the clean air never hurts. You can find air purifiers that have built-in diffusers that'll release relaxing scents, helping your home smell fresher. 

Original price: $46.99

The Pomoron air purifier includes an air ionizer, a HEPA filter, a UV light and an essential oil diffuser, all in one machine. There are four fan speeds and multiple settings, including an ultra-quiet sleep mode.

Original price: $59.99

The Vewior air purifier has a three-stage filter system, consisting of a pre-filter, a HEPA filter and an activated carbon filter to keep your air clean. You can also easily add the scent of your choosing to the built-in oil sponge on the top and the purifier will filter the scent into your space. 

For more deals, visit www.foxnews.com/deals

There are many brands of air purifiers worth checking out. Here are some air purifiers from other stores you could consider. Some stores even have sales of their own right now.

Original price: $1,299

The LG PuriCare is a tower air purifier that is best for rooms up to 512 square feet. Dirty air is pulled in from every direction and clean air is pushed back out by the system's two Clean Booster fans. The purifier is whisper-quiet, making it ideal for living rooms and kids' rooms, and can be controlled from anywhere from the LG ThinQ app. 

Original price: $349

The Alen BreatheSmart Flex purifies rooms that are up to 700 square feet every 30 minutes, and it comes in six unique finishes, from wood to graphite. It's an ultra-quiet machine that won't disturb anyone in your household. You can download the Alen app and control your BreathSmart purifier from anywhere. 

Original price: $139.99

An Airplus air purifier is a powerful purifier that can keep the air clean in homes with pets. It has a two-sided intake setup that filters your air in just 12 minutes. The double-sided system also makes this purifier ideal for larger areas. The air ionizer helps eliminate smells, efficiently cleaning the surrounding air.

Add a fun nightlight and an air purifier combo to your kid's room with the GermGuardian air purifier. The HEPA filter kills 99.97% of germs, dust and allergens in the air, while the three-color nightlight makes any room more fun. Choose from colorful stars, an under-the-sea theme or a jungle-themed projection.