A National Terrorism Advisory System bulletin warned Sunday that there is a "heightened threat environment in the United States" after the military strikes on three key Iranian nuclear sites. 

The bulletin, while not citing any specific threats, said that "low-level cyber attacks against US networks by pro-Iranian hacktivists are likely, and cyber actors affiliated with the Iranian government may conduct attacks against US networks," reports CBS News, which obtained the document before it went public.

The bulletin further notes that "multiple potentially lethal Iranian-backed plots in the United States" have been disrupted by law enforcement since 2020. 

"The ongoing Israel-Iran conflict could also motivate violent extremists and hate crime perpetrators seeking to attack targets," the document adds. 

It further warned that there is a likelihood that violent extremists in the homeland could independently turn to violence if Iran's leadership "issued a religious ruling calling for retaliatory violence against the United States."

Multiple sources told CBS News that intelligence analysts started pulling the document together earlier this month. 

The full document, officially made public Sunday by the Department of Homeland Security, adds that "multiple recent Homeland terrorist attacks have been motivated by anti-Semitic or anti-Israel sentiment, and the ongoing Israel-Iran conflict could contribute to US-based individuals plotting additional attacks."

President Donald Trump has warned Iran against retaliation and called for work toward a peace agreement with Israel, threatening to target more sites in Iran if "peace does not come quickly."

Several foreign terrorist organizations, including HAMAS, Lebanese Hezbollah, the Houthis, and the Popular Front for the Liberation of Palestine, have called for violence against US assets and personnel in the Middle East after Israel attacked Iran, the bulletin added. 

"The Iranian Government has declared the United States complicit for Israel's attack and will almost certainly condemn direct US involvement in the conflict," officials said. 

Meanwhile, law enforcement officials in New York City said Saturday night they were going to deploy more resources to certain areas of the city after the strikes on Iran's facilities. 

"We're tracking the situation unfolding in Iran," the department said on social media. "Out of an abundance of caution, we're deploying additional resources to religious, cultural, and diplomatic sites across NYC and coordinating with our federal partners. We'll continue to monitor for any potential impact to NYC."