The US Department of Home Security (DHS) on Saturday issued a rare National Terrorism Advisory System (NTAS) alert warning about possible Iranian terror and cyber campaigns in retaliation for the US drone strike that killed Iranian military commander Maj. Gen. Qassim Suleimani at Baghdad airport last Friday.

Suleimani was the commander of the Quds Force, the extraterritorial operations branch of Iran’s Islamic Revolutionary Guard Corps (IRGC). The Iranian government and various allied organizations have warned that they plan to retaliate against the US over Suleimani’s death. The DHS warns that “Iran maintains a robust cyber program and can execute cyber attacks against the United States,” adding that such an attack “may come with little or no warning.”

Read more: DHS: Iran maintains a robust cyber program and can execute cyber-attacks against the US