Two fighter jets scrambled over central New Jersey after two aircraft violated airspace restrictions in place because of the United Nations General Assembly meeting.

North American Aerospace Defense Command spokesman John Cornelio said the F-22s intercepted the small civilian planes during two separate incidents over central New Jersey around 11 a.m. Tuesday.

Cornelio says the pilots did not respond to the radio and were forced to land at Central Jersey Regional Airport in Hillsborough. According to an airport representative who would not provide her name to NBCNews.com, both planes left the airport shortly after landing. 

It was unclear if the pilots were detained. 

Obama: US will 'do what we must' to stop Iran getting nuclear weapons

FAA spokesman Jim Peters says the temporary no-fly zones were established around the New York City metropolitan area because of the U.N.  meeting.

Watch the Top Videos on NBCNews.com 

President Barack Obama addressed the U.N. gathering on Tuesday.

More content from NBCNews.com:

• Gray wolf pack in Wash. state will be shot dead after preying on cattle
• Juvenile murderer ruling reopens 'traumatic wounds' for families
• Video: Exonerated man set free after 19 years in prison
• Education Nation: Starkly different visions from Obama, Romney
• Teen picked for homecoming court as prank felt like 'piece of trash'

Follow US News from NBCNews.com on Twitter and Facebook

Courtesy U.S. Air Force

An F-22 Raptor fighter jet flies in a training mission over the Nevada Test and Training Range.

Defense Secretary Leon Panetta on Tuesday lifted flight restrictions for a squadron of F-22 fighter jets that are being deployed to Kadena, Japan, within the next few days.

The F-22s were restricted from flying more than a half hour from any landing area and at higher altitudes after several pilots suffered in-flight symptoms of hypoxia. 

The 18 Kadena-bound fighter jets will fly a northern route over the Pacific that will not take them more than 90 minutes from the nearest landing field. Additionally, they will fly at lower altitudes — nowhere near their 50,000-foot operational capacity. The lower altitude will not put pilots under the same physiological stress as higher altitudes.

Once at Kadena, the stealth aircraft will be put back into the current flight restrictions imposed against all other F-22s. Once again on a short tether, pilots will not be permitted to fly more than 30 minutes from a landing field, and must remain at lower altitudes.

Related: Air Force eyes pressure vests in F-22 oxygen deprivation problem

Flight restrictions will remain in place for all F-22s conducting training missions in the U.S. and those deployed to Qatar and the United Arab Emirates in the Persian Gulf region.

The restrictions will be lifted only when the Pentagon is satisfied the Air Force has positively identified the cause and eliminates the threat of hypoxia for F-22 pilots.

More content from NBCNews.com:

• Obama announces 'reverse bootcamp' for veterans
• Gunman on UConn campus commits suicide
• In Aurora massacre, trial may not shed much light on motive
• Mystery of Utah's 'goat man' is solved
• Day care video shows 9-year-old terrorizing tots

Follow US News from NBCNews.com on Twitter and Facebook

Handout / U.S. Air Force via Reuters file

An F-22 Raptor fighter jet flies in a training mission during Red Flag 12-3 over the Nevada Test and Training Range.

Updated at 8 p.m. ET: The Air Force this week directed F-22 pilots to stop wearing pressure suit vests during routine flights after tests determined the garments could contribute to ongoing oxygen deprivation problems, NBC News has learned.

A senior U.S. military official said that Air Force investigators “haven’t determined definitively that this is the smoking gun that everyone is looking for” but that “this is a significant development.”

During centrifuge testing at Brooks-City Base in Texas, the Air Force was able to recreate some of the hypoxia-like symptoms that pilots have experienced in the F-22, the official told NBC News.

The testers, from the 711th Human Performance Wing, determined that the upper pressure vests do not always deflate properly, making it hard for the pilots to breathe. When tests were done in a high G environment (high levels of acceleration), some pilots could not get their breath at all, the official said.

The official added that the Air Force will continue testing to ensure they “have this situation squared away.”

Lt. Col. Edward Sholtis, a spokesman for the Air Combat Command, said the upper pressure garment is not "the" cause of physiological incidents and that investigators also are looking at the layering of other Aircrew Flight Equipment as contributing to breathing difficulties.

Senator Mark Warner, D-Va., and Rep. Adam Kinzinger, R-Ill., said Wednesday in a joint statement that the F-22 problems are more widespread than earlier reported.

The Air Force told the lawmakers that through May 31 there were 26.43 hypoxia or hypoxia-like incidents per 100,000 flight hours among F-22 pilots -- a rate at least 10 times higher than any other Air Force aircraft, according to the statement.

They said the equipment test results revealed this week were the result of collaboration they recommended with a Navy dive team in Panama City, Fla.

F-22 troubles were widely publicized in a May “60 Minutes” appearance by Virginia Air National Guard Capt. Joshua Wilson and Maj. Jeremy Gordon, who refused to fly the fighter jet and claimed its oxygen system was poisoning them.

"The safety of these pilots and the communities over which they fly should be everyone's paramount concern," Warner said. "The F-22 program has cost $80 billion so far, but the most expensive fighter jet in the world is useless if we cannot ensure the safety of the pilots who fly it."

“As the nation with the strongest military and the brightest minds in the world, we must make certain that we provide our men and women in uniform with the best equipment possible,” Kinzinger said.

In May, Defense Secretary Leon Panetta ordered the Air Force to restrict F-22 flights because of continuing problems with the Raptor's oxygen system. At least 22 pilots suffered from oxygen deprivation while in flight since April 2008.

Panetta ordered that all F-22 flights remain within a "proximate distance" of an airfield in case a pilot should suffer from a hypoxia event and be forced to land. Some F-22s are deployed to southwest Asia.

Panetta also ordered the Air Force to accelerate installment of a backup oxygen system in all F-22s, a process the Air Force does not expect to begin until December. The Air Force awarded a $19 million contract to Lockheed Martin Corp. to install a backup oxygen system in the F-22 Raptor that it makes.

The aircraft were grounded last year temporarily so the Air Force could study its oxygen system.

The Air Force reports that each of the aircraft costs $143 million. The U.S. Government Accountability Office, however, estimates that each F-22 cost taxpayers $412 million, if upgrades and research and development expenses are included.

Courtney Kube is NBC News' Pentagon producer. NBC News' Libby Leist contributed to this report.

More content from msnbc.com and NBC News:

• North Carolina lawmakers move to scale back Racial Justice Act
• Chicago pushes longer school days to raise achievement
• Police hunt surgeon after fatal shooting at NY hospital
• Video: 911 call reports kid behind the wheel
• Cops: Parents left 2 kids bound, blindfolded in Wal-Mart lot

Follow US News on msnbc.com on Twitter and Facebook

Defense Secretary Leon Panetta has ordered the Air Force to restrict flights of its new F-22 stealth fighters because of continuing problems with the aircraft's oxygen system.

At least 22 pilots have suffered from oxygen deprivation while in flight since April 2008.

Panetta on Tuesday ordered that all F-22 flights remain within a "proximate distance" of an airfield in case a pilot should suffer from a hypoxia event and be forced to land. That will force an immediate end to F-22 patrol missions over Alaska.

Panetta also ordered the Air Force to accelerate installment of a backup oxygen system in all F-22s and provide monthly progress reports on efforts to identify the problem with the current oxygen system.  The Air Force does not expect to begin installing automatic backup oxygen systems until December of this year.

Watch the Top Videos on msnbc.com

Handout / U.S. Air Force via Reuters file

A F-22 Raptor fighter jet flies in a training mission during Red Flag 12-3 over the Nevada Test and Training Range.

The Air Force has been unable to determine the cause of the 12 incidents of hypoxia suffered by pilots of the F-22. Pilots have reported wooziness while flying the supersonic jet, considered the most advanced fighter plane in the world.

Some of the military’s top aviators have refused to fly the radar-evading planes because of the oxygen system problems.

The supersonic plane has also been criticized in the past for its high-maintenance costs. 

The Air Force reports that each of the aircraft costs $143 million. The U.S. Government Accountability Office, however, estimates that each F-22 cost taxpayers $412 million, if upgrades and research and development expenses are included.

Jim Miklaszewski is the chief Pentagon correspondent for NBC News. Courtney Kube, NBC's Pentagon producer, and msnbc.com reporter Jeff Black contributed to this report.

More content from msnbc.com and NBC News:

• Cities struggle to keep Memorial Day, Fourth of July celebrations
• Marines sold stolen combat weapons to gangs, China
• Fire captain demoted for Trayvon Martin Facebook post
• Video: Brutal violence escalates in Mexico drug wars
• Shopper bitten by rattlesnake in Wal-Mart

Follow US News on msnbc.com on Twitter and Facebook