The United States faces a "sobering" and "unique moment" in confronting a domestic threat environment that has been heightened since the beginning of the Israel-Hamas war, Deputy Attorney General Lisa Monaco told ABC News in an exclusive interview on Thursday.

Monaco gave the first specifics and detailed look at how that conflict overseas has stoked an already elevated threat situation that many U.S. officials are describing as the most challenging since before 9/11.

The FBI has had to run down more than 1,800 reports "of threats or other types of tips or leads" related to the war that began on Oct. 7 with Hamas' terror attack in Israel, Monaco said. The bureau now has more than 100 investigations currently opened in some way tied to the conflict.

The biggest concerns are lone wolves and small groups taking action with little to no notice, according to Monaco.

"I think we're in a unique moment where what we're most worried about -- those of us in the national security and law enforcement community -- are individuals or small groups who are often radicalized online and who are motivated by and influenced by a range of ideologies, from foreign terrorism and foreign terrorist organizations to domestic grievances," Monaco told ABC News Chief Justice Correspondent Pierre Thomas in an exclusive sit-down that will air Sunday on "This Week."

"Oftentimes what we're seeing in the most lethal form is from racially or ethnically-motivated ideologies," the deputy attorney general said.

While Monaco noted that in many cases the threats or tips received by the FBI have been "resolved without incident," the sheer volume has caused "a lot of strain" on U.S. law enforcement, as agents and prosecutors chase down potential leads across the country in tandem with state and local partners.

"These are threats, they're hoaxes, they can involve claims of terrorist financing," Monaco said, describing the range of what authorities are reviewing. "So that is the volume -- the significant uptick in the volume and frequency of the types of reports we're getting."

Monaco cited the "searing images" of Hamas' terror attack on Israel as well as accounts of "parents huddled with their children in safe rooms, loved ones being killed in front of each other's children -- literally ripped from their parents and being kidnapped" and the more than 1,200 people killed, including more than 30 Americans, as evoking emotional reactions across the globe that have in turn driven a "very significant uptick in threats" and "actual violence" inside the U.S.

"We've seen individuals who are taking, I think, twisted inspiration from those images," she said.

Monaco also noted that the Justice Department has seen a surge in threats targeting political and government officials. This week alone, she pointed to cases against individuals accused of threatening a U.S. Supreme Court justice, FBI agents and three presidential candidates.

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