Read this posting for a very detailed and informative writeup on the Islamic jihadists arrested in Lodi, California. Lots of links to follow in the posting.
The posting begins:

As put by Rusty at Jawa Report, “Four men have been arrested in Lodi California, two on suspicion of aiding al Qaeda and two on immigration violation charges. One of the most worrisome aspects of this story is that the two arrested on immigration charges were in the process of starting a religious school. Guess which religion?”
So while we sleep, sleeper cells aren’t yawning. From hospital-based terror plots to school lunches, an office building, an airport, or a shopping center, it’s all fodder for jihadis. And for a flavor of Islamists agenda for America, you need go no further than the Islamist’s favorite group, CAIR, whose board member, Imam Siraj Wahaj calls for replacing the American government with a caliphate, and warns that America will crumble unless it “accepts the Islamic agenda.” Are you listening yet? You may be but our politicians and the liberal MSM aren’t…

The posting also includes a link to this key conclusion written at the end of this Captain’s Quarters posting:

This also shows the fallacy of the “they hate us because they don’t know us” crowd. The Hayats and the other fanatics in Lodi had the freedom to practice their religion and earn a decent living in California — certainly they made a higher standard of living there than they could have expected in Pakistan or Afghanistan, especially before the Taliban were ejected by American military action. They don’t hate us because they misunderstand us. They hate us because all they know is hate, and outreach and kind words don’t make a damned bit of difference to fanatics.
It’s time we understood the difference between moderates and fanatics, and the difference between youthful indiscretions and outright treason. A free society can handle moderates and survive youthful indiscretions, but it cannot abide fanatics who commit treason. We need to make that abundantly clear in the manner which we handle the latter.

Now go read all the various links to get better informed.
Then read this LA Times report and see how these arrests may only be the tip of the iceberg.