Many in the liberty movement are well aware of the Obama Administration's ability to assassination American citizens abroad if they are considered terrorists.  However in a recent interview in the Washington Times, Obama advisor John Brennan has revealed there might be as many dozens of US citizens targeted on a assassination hit list:

"There are, in my mind, dozens of U.S. persons who are in different parts of the world, and they are very concerning to us," said John O. Brennan, deputy White House national security adviser for homeland security and counterterrorism.

As usual, Glenn Greenwald has an excellent writeup on this.