"Nuclear umbrella" is not a well-defined term. It is the set of promises the US made to non-nuclear states. It made a set of guarantees to some set of nations (e.g. NATO++), and a set of assurances to other states, like Ukraine.

Our reneging on our assurances indicates weakness in our guarantees, which risks a proliferation spiral.

For example, NATO's Article 5 can be legalesed the same exact way you're trying to legalese the Budapest Memorandum.

Budapest Memorandum:

> The Russian Federation, the United Kingdom of Great Britain and Northern Ireland, and The United States of America reaffirm their commitment to seek immediate United Nations Security Council action to provide assistance to Ukraine, as a non-nuclear-weapon state party to the Treaty on the Non-Proliferation of Nuclear Weapons, if Ukraine should become a victim of an act of aggression or an object of a threat of aggression in which nuclear weapons are used.

NATO Article 5:

> The Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all and consequently they agree that, if such an armed attack occurs, each of them, in exercise of the right of individual or collective self-defence recognised by Article 51 of the Charter of the United Nations, will assist the Party or Parties so attacked by taking forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area.

Both agreements promise assistance. Do you think the US's view that your position of "not our problem" qualifies as assistance under the Budapest memorandum, but that somehow "not our problem" would not qualify as assistance under Article 5?

I'm curious for your opinion, though it doesn't matter much. The reality is that all of this is destroying the umbrella and its civilization-protecting purpose: https://www.cnbc.com/2026/08/19/nuclear-proliferation-defens...