U.S. Officials Fear Qaeda Trying to Produce Lethal Toxin Bombs.

Be very worried. We must not leave Afghanistan and anywhere else where El Qaeda network exists. Yemen it would be the next trouble spot to take on. This war is going to be a long one.
Refer to excerpt that explains the very deadly toxin.

For more than a year, according to classified intelligence reports, Al Qaeda’s affiliate in Yemen has been making efforts to acquire large quantities of castor beans, which are required to produce ricin, a white, powdery toxin that is so deadly that just a speck can kill if it is inhaled or reaches the bloodstream.

Read the New York Times by Eric Schmitt and Thom Shanker