The president can only exercise policies to execute those laws.

From: https://www.whitehouse.gov/briefing-room/presidential-actions/2023/02/23/memorandum-on-united-states-conventional-arms-transfer-policy/

If the United States determines at any time that a transfer is no longer in accordance with United States foreign policy objectives, national security goals, or legal obligations, the United States may cease the transfer of or future support for a transferred defense article or service.

Biden could act unilaterally here.

This is elementary school civics in the US.

Yes, and he needs a declaration of war to go to war. 🙄 Just because your education ended with an elementary school reading of the constitution, doesn't mean that's how the country operates in practice.

"Checks and balances" exist in name only. Sure the supreme court or congress could strike down new social programs, but war and spy powers exist independently from the legislative and judicial branches.