[SLB]

Most UAV's are almost impossible to detect from the ground. If they are powered by battery instead of gasoline they are almost noiseless. They will be painted on the underside to blend in with the sky, a light blue or grey. Their radar cross section is so small they will be lost in ground clutter such as birds and trees. For a trained observer to spot one is more luck than skill usually they just happen to glance in the right place at the right time. The payload these little rascals can carry is amazing. I have worked some programs with them and for a recon platform they are one of the most versatile we have. As a platform for delivering some type of bio or chem agent they probably have no equal. Chemical would be the most likely, but one never knows.

[harpseal]

It is possible to create a UAV with off the shelf components. The simplest are the standard radio controlled model airplanes. Upscaling just slightly and one has an effective bioweapons delivery system. all one needs are the plans and one can assemble such a UAV here in the US with hardly any smuggled parts needed.