They were planning to bring down an entire housing block, killing up to 120 people, after the election. The FBI arrested three loons and said that they got everyone involved with the plot.
If all of this is true, then good job, FBI.
The FBI learned the “blow up the housing project” trick from the Russian successors to the KGB.
The Russian secret service blew up a Moscow apartment complex and blamed it on Chechen extremists.
http://www.nybooks.com/articles/2012/11/22/finally-we-know-about-moscow-bombings/
The FBI undoubtedly has dozens of these schemes as works in progress to keep the American public terrorized, divided against each other and docile.