(CNN) President Donald Trump has seized on protests in Portland, Oregon, and Kenosha, Wisconsin, in the ramp-up to the presidential election, casting them as dangerous to surrounding communities and threatening to respond with the force of the federal government as he again elevates his message of law and order.
But former government officials argue the situation on the ground as it stands doesn't warrant the forced deployment of federal law enforcement that Trump has foreshadowed.
"We're ready, willing and able to send in a massive group of people that are really highly trained," Trump said at a roundtable in Kenosha on Tuesday, singling out Portland, Chicago and New York before looking over to his attorney general, William Barr, and adding, "I hope they'll call, eventually they'll call, and at some point, Bill, we'll just have to do it ourselves."
Federal law enforcement personnel are already stationed in cities nationwide -- including Portland and Kenosha -- to execute on a range of missions, like protecting federal buildings and investigating federal crimes related to riots, oftentimes with the assistance of state and local authorities. Amid ongoing unrest, however, the Trump administration is continuing to wield the power of the federal government to crack down on protests that have at times turned violent.
Acting Homeland Security Secretary Chad Wolf warned this week that federal law enforcement would redouble their activity in Portland if unrest continued, escalating the feud between city officials and the administration.
Wolf has publicly discussed the deployment of Justice Department personnel as well as those within his own department, raising questions about what exactly might be deployed. The Department of Homeland Security, in particular, ultimately has broad authority and the deployment of personnel will depend on the circumstances, according to former DHS officials.
Earlier this summer, DHS deployed personnel to Portland to protect federal buildings and personnel, which falls under the department's jurisdiction. Trump, in a Fox News interview Monday night, said the department did a "great job" protecting the federal courthouse.
In a letter to Portland Mayor Ted Wheeler Monday, Wolf suggested a future deployment of federal law enforcement to "protect our American citizens."
"We are standing by to support Portland. At the same time, President Trump has made it abundantly clear that there will come a point when state and local officials fail to protect its citizens from violence, the federal government will have no choice but to protect our American citizens," Wolf wrote.
Wheeler responded to the letter saying, "Mr. Wolf's letter is grandstanding."
Former Homeland Security Secretary Jeh Johnson, who served in the Obama administration, noted there's a lot of nuance to take into account on legal authorities. "I could envision certain compelling circumstances under which it'd be appropriate for DHS to send its law enforcement to a city without a request of the governor and mayor," Johnson told CNN. "I do not believe those circumstances exist in Portland at the moment."
DHS has the authority to protect federal facilities and enforce specific federal laws, but it's not a federal police force, according to Carrie Cordero, a senior fellow at Center for a New American Security and CNN legal analyst, adding that the department cannot force a locality "to take the law enforcement activity that it would prefer, as either a public safety or policy preference."
"It's one thing for the DHS secretary to offer assistance to state and local authorities when they need and want it; it's another to threaten -- as the letter does -- to step in in place of state and local authorities," Cordero said.
The Department of Homeland Security, the third-largest federal department, has a sprawling mission that includes immigration enforcement, cyber security, counterterrorism, among other tasks. The Homeland Security secretary has the authority to designate DHS personnel to other tasks, such as Immigration and Customs Enforcement or Customs and Border Protection officers for the purpose of protecting federal property.
In another move to branch out its authority, DHS announced a task force centered on protecting American monuments, memorials and statues ahead of the July 4th weekend and in the wake of Trump's call to use federal law enforcement to protect monuments.
"We won't stand idly by while violent anarchists and rioters seek not only to vandalize and destroy the symbols of our nation, but to disrupt law and order and sow chaos in our communities," Wolf said in a statement at the time.
The department's federal law enforcement personnel can also be deployed at the request of state and local authorities. For instance, large events like the Super Bowl or political conventions can be designated as special events to allow for additional cooperation of local, state and federal authorities to provide security.
Under the Trump administration, DHS has also surged personnel to the southwest border to support the department's immigration and border security agencies.
But there is "little-to-no precedent for DHS" to deploy resources for the purposes of maintaining law and order in a city if not requested by the locality, said former DHS chief of staff and CNN contributor Miles Taylor, adding that it "would put the department in a very, very unusual position."
"If such an intervention is conducted, it would seem vastly more appropriate for it to be done under the auspices of the Justice Department and the Attorney General (as the nation's chief law enforcement officer), not the Homeland Security Secretary. This is starting to put DHS in uncharted territory," he said.
Justice Department personnel have already surged to places that have seen unrest in recent days. In Kenosha, more than 200 agents and marshals from agencies including the FBI, US Marshals Service and Bureau of Alcohol, Tobacco, Firearms and Explosives were dispatched to help local authorities as they responded to rioting in the streets of the city.
Kenosha County Sheriff David Beth, who had requested the federal backup as unrest spread in the wake of the shooting of Jacob Blake by a Kenosha police officer, called the assistance "unbelievable" and praised Trump and Barr at the roundtable in the city Tuesday.
In Portland, the US Marshals, who are regularly tasked with courthouse security, are part of the mix of federal law enforcement officers who've been repelling attacks from rioters at a complex of federal buildings in the city's downtown nightly.
The FBI is also assisting local authorities in both cities with investigations into shooting deaths involving protesters in recent days, according to local and federal officials.
It would be "unusual" and impractical, however, for federal agents to assume the role of peacekeepers in a city that they're not invited into, like Portland.
"It really is a state and local mission," said Greg Brower, a former Nevada US attorney and senior FBI official. "In the absence of a state or a local jurisdiction requesting federal assistance in some way, then the federal government almost always really has no business in inserting itself."
"It has to be understood for what it is, which is just political rhetoric as we get close to a presidential election," Brower said.