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US Department of Homeland Security says it is probing a cyber breach at information-sharing network

By Thomson Reuters Jul 2, 2026 | 4:01 PM

By Raphael Satter

WASHINGTON, July 2 (Reuters) – The Department of Homeland Security said on Thursday it ​was investigating a breach in an ‌unnamed information-sharing network.

In a statement, DHS said there had been a “recent cyber incident” involving an “unclassified legacy information sharing environment” ‌but ​did not provide ⁠further details and ⁠did not respond to follow-up questions.

GovExec, which first reported the news, said the breach affected the Homeland ​Security Information Network, a platform used to share sensitive but ⁠unclassified data with ⁠partners, including foreign law ​enforcement, local authorities, and other organizations. ​GovExec, which cited two unnamed sources ‌familiar with the matter, said the breach was believed to have occurred between late May and ⁠early June.

U.S. Senator Mark Warner, the top Democrat on the Senate Intelligence Committee, said ⁠the information ‌carried in the network, “while ⁠not classified, is highly ​sensitive, ‌and its exposure risks national ​security.”

He called ⁠on DHS and the Justice Department to “thoroughly investigate” who breached the network and what they compromised.

(Reporting by Raphael Satter in WashingtonEditing by ​Matthew Lewis)