The Department of Homeland Security (DHS) issued a terrorism threat assessment bulletin on Iran on Saturday, Jan. 4, saying that there is still no “specific, credible threat” to the U.S. homeland, but warning Americans to step up their vigilance. 

The DHS bulletin followed the U.S. strike that killed the head of Iran’s Islamic Revolutionary Guard Corps—Maj. Gen. Qassem Soleimani. Iranian leadership vowed to seek revenge after Soleimani’s death.

“At this time we have no information indicating a specific, credible threat to the homeland,” DHS said, but cautioned, “Iran and its partners, such as Hizballah [Hezbollah], have demonstrated the intent and capability to conduct operations in the United States.”

The bulletin laid out a host of potential scenarios for danger, including individual attacks.

DHS also warned that Iran, which “maintains a robust cyber program,” is capable of “carrying out attacks with temporary disruptive effects against critical infrastructure in the United States” and “likely views terrorist activities as an option to deter or retaliate against its perceived adversaries.”

Iran has threatened “harsh retaliation” after the U.S. airstrike. Officials said Soleimani has been responsible for the death of hundreds of U.S. troops in the Middle East over the years.

The U.S. Defense Department said Soleimani “was actively developing plans to attack American diplomats and service members in Iraq and throughout the region.” It also accused Soleimani of approving the orchestrated attack at the U.S. Embassy in Baghdad.

“We took action last night to stop a war. We did not take action to start a war,” President Trump said Friday, adding it “should have been done long ago.”

President Trump on Saturday said the United States has targeted 52 Iranian sites and was prepared to strike “very fast and very hard” should Iran takes action of retaliation. 

“The new @DHSgov NTAS Bulletin on the threat landscape was issued to inform & reassure the American public, state/local governments & private partners that DHS is actively monitoring & preparing for any specific, credible threat, should one arise,” acting Secretary Chad Wolf wrote in a tweet.