This week’s attempted attack on a cartoon contest in Garland, Texas, raised concerns about the threat of terrorist activity by individuals in the U.S. inspired by the propaganda of the Islamic State and other extremists. Some other recent cases:

• A Kansas man, John T. Booker, was charged April 10 with plotting a suicide bomb attack at Fort Riley. Prosecutors allege he told an FBI informant he wanted to kill Americans and engage in jihad. Alexander Blair, was charged with failing to report Booker’s plans to authorities.

• Two New York City women – Noelle Velentzas and Asia Siddiqui – were arrested April 2 on charges they plotted to wage jihad by building a homemade bomb and using it for a Boston Marathon-type attack. Officers recovered items including gas tanks, a pressure cooker, notes on the recipes for bomb-making and jihadist literature, court papers said.

• An Illinois Army National Guard soldier and his cousin were arrested in March on charges of plotting terrorist attacks in support of the Islamic State. A federal complaint said Jonas Edmonds planned to attack an Illinois military facility while Hasan Edmonds joined Islamic State fighters.

• In February, federal authorities charged three New York City men with planning to travel to Syria to join the Islamic State. Abdurasul Hasanovich Juraboev, Akhror Saidakhmetov and Abror Habibov were indicted on charges of conspiracy to provide material support to a foreign terrorist organization and travel document fraud.

• A Ohio resident, Christopher Lee Cornell, was arrested in January and accused of plotting to attack the U.S. Capitol. He later said in a TV interview that he wanted to shoot President Obama in support of the Islamic State.

• Mufid Elfgeeh, a naturalized American citizen born in Yemen and living in Rochester, New York, was arrested last year on charges of trying to aid Islamic State extremists.