Quickly prevent POTUS from initiating military or nuclear operations?

Question

As Pelosi warns Trump could be impeached for a second time if he does not leave office imminently and willing, she has expressed in a letter about two things which stems this question...

1. Taking "available precautions for preventing an unstable president from initiating military hostilities or accessing the launch codes and ordering a nuclear strike"; and also
2. Her having "had spoken to the top United States military commander about taking precautions to ensure Republican President Donald Trump cannot initiate hostilities or order a nuclear attack in his remaining 12 days in office".

Question: Given there is only 11 days left in the current presidency, are there any legal/technical methods that could prevent the President from his powers as Commander in Chief, or from being able to initiate any correlated military or nuclear actions?

Context Related Stuff

• Is congress' mere "pursing impeachment" of a POTUS enough to prevent him from the correlated duties of initiating these sort of operations, or does he actually need to be convicted first to get this outcome.

• Is Pelosi's (and/or majority of congress) letters and talks with top military commanders actually effective in doing something here that could actually prevent this.

• To do such a thing "quickly" would that require VP, Senate, and House all to work together or any combination perhaps, etc.

• Per the US Constitution it seems there isn't anything that can prevent this so are there other avenues and such that can be explored for this sort of outcome in a timely manner.

• Would any of the recent "extraordinary" events help open any technical loopholes for this outcome.

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Supporting Resources

• Presidential Authority as Commander in Chief of the Air Force

  • The document citing "U.S. Const. art. I, § 2, cl. 1" and a few others too

• Commander in Chief Clause

  • "would only prohibit Congress from literally placing someone other than the President atop the U.S. military hierarchy, it presumably also means that Congress cannot insulate parts of the military from the President’s superintendence or interfere with the President’s supervisory role, lest Congress have the power to effectively undermine the President’s command authority"

Answer 1

Given there is only 11 days left in the current presidency, are there any legal/technical methods that could prevent the President from his powers as Commander in Chief?

Yes. These methods are impeachment, the 25th amendment, and the duty of military officers not to obey illegal orders. The last is not deterministic, however, because military officers may disagree about the legality of some orders. Furthermore, an officer who disobeys an illegal order risks punishment if the order is subsequently found to be legal, so it really is not something that anyone should count on.

Is congress' mere "pursing impeachment" of a POTUS enough to prevent him from the correlated duties of initiating these sort of operations?

No. That would allow congress to remove power from the president (albeit temporarily) too easily.

Or does he actually need to be convicted first to get this outcome?

Yes.

Is Pelosi's (and/or majority of congress) letters and talks with top military commanders actually effective in doing something here that could actually prevent this.

Not from a legal perspective.

To do such a thing "quickly" would that require VP, Senate, and Congress all to work together or any combination perhaps, etc.

Invoking the 25th requires the VP's agreement. Impeachment and conviction requires neither the VP's agreement nor participation. Impeachment does however require the participation (but not agreement) of the chief justice. (The senate is part of congress, by the way.)

Per the US Constitution it seems there isn't anything that can prevent this so are there other avenues and such that can be explored for this sort of outcome in a timely manner.

I don't understand this point. Prevent what?

Would any of the recent "extraordinary" events help open any technical loopholes for this outcome.

Recent events have changed the political landscape, and perhaps constitute factual grounds for impeachment or prosecution that obviously did not exist before the events occurred. They do not change the constitutional processes at all.