The criminal probe of Hillary Clinton’s emails is zeroing in on messages between Washington and American diplomats in Islamabad over drone strikes in Pakistan, according to a published report.

The emails were part of a secret deal giving the State Department more say in the targeting of CIA drone strikes, congressional and law-enforcement officials briefed on the FBI told the Wall Street Journal.

They were handled on a non-classified government computer system, and some of the emails were forwarded to Clinton’s personal email account, routed to the server at her New York home. The server has been seen as highly vulnerable to hacking.

Law-enforcement and intelligence officials told the newspaper the State Department’s discussions of CIA drone targeting — though vaguely worded, without mentioning “drones” or details about targets, should have been handled by a more secure government computer system.

State Department officials reportedly told FBI investigators they used the less-secure system occasionally when decisions about imminent strikes had to be made quickly, and the U.S. diplomats didn’t have access to the more-secure system, when they were away from the offices.

The CIA drone campaign has otherwise been conducted under strict classification rules, with U.S. officials barred from discussing strikes publicly.

Clinton clinched the Demnocratic nomination this week. Polls have shown voters doubt Clinton’s integrity, while Republican Donald Trump has taken to calling her “Crooked Hillary,’’ saying he doubts a Democratic-led Justice Department will indict her. The newspaper reported that several law-enforcement officials said they don’t expect any criminal charges to be filed against her, though the FBI is expected to interview her this summer.

Clinton campaign spokesman Brian Fallon told the Wall Street Journal: “If these officials’ descriptions are true, these emails were originated by career diplomats, and the sending of these types of emails was widespread within the government.”

The newspaper said there is no evidence the emails were intercepted by Pakistani intelligence officials. The drone strikes on terrorist targets in the tribal areas neighboring Afghanistan that have long been used as a Taliban refuge are highly controversial in Pakistan, though they have been seen as effective by the Obama administration, which dramatically increased the use of drone strikes.