In addition because the providers and cables are owned and operated by private companies the government would have a very hard time convincing telcos to do that.
Hell even internally you can’t with every major city having 2 or 3 places where providers can connect with Google, Amazon, Facebook, Cloudflare, Akamai. Not to mention all the private peering locations.
From a political POV, make legislation that says registered telcos must turn off telecommunications equipment connected to non US locations or black hole non us traffic when entering the country when requested by a government.