Pentagon officials are holding informal discussions about how the Department of Defense would respond if Donald Trump issues orders to deploy active-duty troops domestically and fire large swaths of apolitical staffers, defense officials told CNN.

Trump has suggested he would be open to using active-duty forces for domestic law enforcement and mass deportations and has indicated he wants to stack the federal government with loyalists and ?clean out corrupt actors? in the US national security establishment.

Trump in his last term had a fraught relationship with much of his senior military leadership, including now-retired Gen. Mark Milley who took steps to limit Trump?s ability to use nuclear weapons while he was chairman of the Joint Chiefs of Staff. The president-elect, meanwhile, has repeatedly called US military generals ?woke,? ?weak? and ?ineffective leaders.?

Officials are now gaming out various scenarios as they prepare for an overhaul of the Pentagon.

?We are all preparing and planning for the worst-case scenario, but the reality is that we don?t know how this is going to play out yet,? one defense official said.

Trump?s election has also raised questions inside the Pentagon about what would happen if the president issued an unlawful order, particularly if his political appointees inside the department don?t push back.

?Troops are compelled by law to disobey unlawful orders,? said another defense official. ?But the question is what happens then ? do we see resignations from senior military leaders? Or would they view that as abandoning their people??

It?s unclear at this point who Trump will choose to lead the Pentagon, though officials believe Trump and his team will try to avoid the kind of ?hostile? relationship he had with the military during his last administration, said a former defense official with experience during the first Trump administration.

?The relationship between the White House and the DoD was really, really bad, and so ? I know it?s top of mind for how they?re going to select the folks that they put in DoD this time around,? the former official said.

Defense officials are also scrambling to identify civilian employees who might be impacted if Trump reinstates Schedule F, an executive order he first issued in 2020 that, if enacted, would have reclassified huge swaths of nonpolitical, career federal employees across the US government to make them more easily fireable.

Secretary of Defense Lloyd Austin said on Tuesday that ?I totally believe that our leaders will continue to do the right thing no matter what. I also believe that our Congress will continue to do the right things to support our military.?

?The enemy from within?

Top of mind for many defense officials is how Trump plans to wield American military power at home.

Trump last month said the military should be used to handle what he called ?the enemy from within? and ?radical left lunatics.?

?I think it should be very easily handled by, if necessary, by National Guard, or if really necessary, by the military, because they can?t let that happen,? he added, referring to potential protests on Election Day.

Several former senior military officials who served under Trump have sounded the alarm in recent years about his authoritarian impulses, including Milley and retired Gen. John Kelly, Trump?s former White House chief of staff. Kelly said before the election that Trump fits ?into the general definition of fascist? and that he spoke of the loyalty of Hitler?s Nazi generals.

There is not much the Pentagon can do to pre-emptively shield the force from a potential abuse of power by a commander in chief. Defense Department lawyers can and do make recommendations to military leaders on the legality of orders, but there is no real legal safeguard that would prevent Trump from deploying American soldiers to police US streets.

A former senior Defense Department official, who served under Trump, said he believes it is likely that additional active-duty forces will be tasked with assisting Customs and Border Protection at the southern border.

There are already thousands of forces at the border, including those with active duty, National Guard, and the Reserves. The Biden administration sent 1,500 active duty forces last year, and later sent several hundred more.

But it is also possible, the former official said, that forces could be sent into American cities if asked to help with the mass deportation plan Trump mentioned repeatedly on the trail.

Domestic law enforcement agencies ?don?t have the manpower, they don?t have the helicopters, the trucks, the expeditionary capabilities? that the military brings, he said. But he emphasized that the decision to send active-duty forces into American streets cannot be taken lightly.

?You can never water that down, you can never say with a straight face that it?s not a big deal. It is a big deal,? the former senior official said. ?But it?s the only way to address issues at scale.?

Separately, an Army official told CNN they could imagine a Trump administration ordering several thousand more troops to support the border mission but warned it could hurt the military?s own readiness to deal with foreign threats.

The president?s powers are especially broad if he chooses to invoke the Insurrection Act, which states that under certain limited circumstances involved in the defense of constitutional rights, a president can deploy troops domestically unilaterally.

A separate law ? the Posse Comitatus Act ? seeks to curb the use of the military to enforce laws unless authorized by Congress. But the law has exceptions for rebellion and terrorism, which ultimately gives the president broad leeway in deciding if and when to invoke Insurrection Act.

Trump reportedly considered invoking the Act in 2020 to quell protests after the death of George Floyd.

?If the city or state refuses to take the actions that are necessary to defend the life and property of their residence, then I will deploy the United States military and quickly solve the problem for them,? he said at the time.

Civilian employees at risk

In a video posted last year, Trump said if elected he would ?immediately re-issue my 2020 Executive Order restoring the President?s authority to remove rogue bureaucrats?we will clean out all of the corrupt actors in our National Security and Intelligence apparatus, and there are plenty of them.?

The Pentagon is already bracing for the policy change.

?My email has been inundated on this topic,? one defense official said of Schedule F. ?Definitely going to be a busy couple months.?

After Trump issued Schedule F the first time, late into his last term, the Pentagon and other federal agencies were tasked with making lists of which employees would be moved into that category. At the time, defense officials tried to include as few civilian employees as possible to limit the impact to the workforce, sources said. The department is making similar lists now.

The Office of Personnel and Management issued a rule in April that aimed to strengthen guardrails protecting federal employees. But ?there are still ways a new administration could work around these protections,? a defense official said, even if it might take several months to do so.

Austin has warned repeatedly about the risk of political abuse of the military. In July, he said in a memo that it is ?necessary to secure the integrity and continuity of the civilian workforce by ensuring that DoD career civilian employees, like their uniformed counterparts, are shielded from unlawful and other inappropriate political encroachments.?

He added that career civil servants are tasked with ?maintaining strict political neutrality focused on loyalty to the Constitution and laws of the United States.?

And on Wednesday, he wrote in a message to the force that the US military will obey only lawful orders.

?As it always has, the US military will stand ready to carry out the policy choices of its next Commander in Chief, and to obey all lawful orders from its civilian chain of command,? he wrote. ?You are the United States military-the finest fighting force on Earth-and you will continue to defend our country, our Constitution, and the rights of all of our citizens.?

In the State Department, Secretary Antony Blinken said in an email to members of the workforce Friday that he will make clear to the incoming Trump administration that ?you are all patriots.?

The message, obtained by CNN, acknowledged that ?transitions can be periods of uncertainty that raise questions about what comes next for our work around the world, for the State Department itself, and for its people.?

It Is a seemingly pointed message. The State Department saw some of its top career officials targeted as part of Trump?s first impeachment and there was a significant departure of career diplomats during the first Trump administration.

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