The FBI is carrying out an investigation on a potential plan to carry out a terrorist attack on U.S. soil, according to the CNN.

An FBI source told the US news-agency that the target of the terrorists was LAX, Los Angeles’ international airport.

CNN claims that the investigation began when telephone conversations and other information pointed to the possibility that the plan has already been set in motion.

TSA has issued memos about increased security measures on airports across the country.

A national security advisor has not made any further comments about a possible terrorist plan, but has sufficed to say that security measures have been increased.