In the years since the Sept. 11 terrorist attacks, the FBI has routinely relied on undercover operations similar to the one that led to the arrest of Christopher Lee Cornell, also known as Raheel Mahrus Ubaydah, on Wednesday.

Cornell told an FBI informant they should "wage jihad" and showed his plans for bombing the Capitol and shooting people, according to a criminal complaint. The FBI also said Cornell expressed his support for the Islamic State.

Some details on such sting operations:

THE FBI'S POSITION:

The FBI sees such sting operations as vital tools in preventing acts of terrorism and appropriate to use against those who have expressed an inclination toward violence. The targets come to the attention of the authorities in varied ways, sometimes through information from a confidential FBI informant or because of online writings that promote jihad or profess allegiance to terrorist groups.

DECRIED BY DEFENSE LAWYERS:

Defense attorneys frequently challenge the operations in court, contending that their clients were entrapped and suggesting that agents are taking advantage of a defendant's misguided thoughts or mental illness. They accuse investigators of effectively grooming them into plotting acts of terror.

HOW THE STINGS WORK:

Typically, undercover agents pose as conspirators and discuss terror plots and targets with suspects. Arrests are often made immediately after the person is provided with weapons or what he believes to be explosives. Federal authorities say the targets often have opportunities to back out of the plot.

SOME EXAMPLES:

— In 2012, a man plotted to detonate a suicide bomb at the U.S. Capitol. He had communicated with undercover agents posing as al-Qaida operatives and was then arrested after putting on what he thought was an explosive-laden suicide vest.

— A Kansas man who was under investigation for six months after making statements about wanting to commit "violent jihad" was arrested in 2013. Authorities say he drove a vehicle loaded with what he thought were explosives to a Wichita airport. He is awaiting trial.

— In Boston, a man plotted with undercover agents to fly remote-controlled planes packed with explosives into the Pentagon and U.S. Capitol. He was arrested after federal employees posing as members of al-Qaida delivered grenades, machine guns and plastic explosives to him.

— Near Cleveland in 2012, five men described as anarchists plotted to blow up a bridge with fake plastic explosives provided by an undercover agent. The men were arrested when one of them tried to "detonate" the fake bomb with a cellphone.

— In 2009, four men were arrested for scheming to blow up New York City synagogues remote-controlled bombs and to shoot down military cargo planes with heat-seeking missiles. An informant provided the men with fake bombs and an inert shoulder missile launcher.

THE RESULTS:

Defense arguments have repeatedly failed with judges, and the stings have led to many convictions. The Justice Department typically points to communications that they say show the suspect held serious aspirations to commit violence. Some judges have expressed reservations about the tactics. In 2011, U.S. District Judge Colleen McMahon in New York said in sentencing one defendant to 25 years in prison that the government "created acts of terrorism" out of fantasies, bravado and bigotry.