According to NBC News, Iran delivered a message to President Trump through an intermediary at last week’s G7 Summit in Canada, warning that it would activate sleeper-cell terrorist groups within the United States if Iran or its nuclear facilities were attacked.

In response, the Trump administration—along with federal, state, and local law enforcement agencies in key cities across the country—is on high alert for possible retaliation on U.S. soil.

Earlier today, the Department of Homeland Security released a statement warning that the ongoing conflict with Iran has created a “heightened threat environment” within the United States.