A series of emails between American diplomats in Pakistan and Washington over drone strikes are the focus of the criminal probe involving presumptive Democratic presidential nominee Hillary Clinton's handling of classified information, according to a report Thursday by The Wall Street Journal. The emails in 2011 and 2012 were sent through a "computer system for unclassified matters" that gave the State Department input into whether a Central Intelligence Agency drone strike went forward, congressional and law enforcement officials briefed on the FBI probe told the Journal. Some of those emails were then sent by then-Secretary of State Clinton's aides to her personal email account and private server, officials told the Journal. The vaguely worded messages, however, didn't mention the "CIA," "drones" or details about the targets, the Journal reported. The emails were written within the often-narrow time frame in which State Department officials had to decide whether or not to object to drone strikes before the CIA pulled the trigger, officials told the newspaper.