Emails involving planned drone strikes in Pakistan were fowarded to Hillary Clinton Hillary Diane Rodham ClintonJeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Momentum growing among Republicans for Supreme Court vote before Election Day Warning signs flash for Lindsey Graham in South Carolina MORE's personal email account and are at the center of an FBI investigation, The Wall Street Journal reports.

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A series of emails between American diplomats in Islamabad and their superiors in Washington involving the drone strikes sent in 2011 and 2012 were forwarded by Clinton's aides to her personal email account and routed to the private server she kept at her home while secretary of State.

Officials told the Journal the messages were vaguely worded and didn't mention "CIA" or "drones" or details about militant targets.

Those emails were sent via the "low side" computer system for unclassified matters as part of an arrangement that gave the State Department more input in whether CIA drone strikes went forward.

State Department officials told the FBI they used the less-secure system occassionally when decisions about imminent strikes had to be relayed quickly and U.S. diplomats in Pakistan or Washington didn't have ready access to a more secure system.