I don't believe that anybody is suggesting that the CIA or NSA should request search warrants for non-citizens located outside of the US. Even if you had probable cause the courts would just be perplexed that you were coming to them with something from outside of the country.

(Many people, myself included, think that there is something wrong with how we are currently handling those situations, but search warrants for non-citizens outside of the country are obviously not the answer we are looking for there.)

Domestic terrorists? Get a warrant.