Congress has approved legislation that would prevent any president from withdrawing the United States from NATO without approval from the Senate or an Act of Congress. The measure, spearheaded by Sens. Tim Kaine (D-Va.) and Marco Rubio (R-Fla.), was included in the annual National Defense Authorization Act, which passed out of the House on Thursday and is expected to be signed by President Biden.
Congress has the power to declare war. The president being commander-in-chief does not mean he can do whatever he please with the U.S army as its own personal force. The president is meant to follow the constitution, even as commander. If the president ignores treaties and war declarations, I would argue the president is the one violating the separation of powers, and not congress by hypothetically enforcing the powers given to them by the constitution. By this logic, whoever controller the army should have absolute power, being commander-in-chief and all. I like how you slipped past my initial post by completely ignoring that the constitution grants congress influence over foreign policies by citing the president control over the armed forces as this unalienable right. Why have treaties then? Why have declaration of war? I think you might be slightly biased in your argument. The president was never the sole responsible for foreign policies, even though the executive branch had a lot of influence over those in recent times.
The Supreme Court has specifically made this point: The President “may not disregard limitations that Congress has, in proper exercise of its own war powers, placed on his powers.” Hamdan vs Rumsfeld (2006).
Just because the President is commander-in-chief does not mean he has plenary power over everything related to the military and it’s use.