How can a country guarantee to not join an organization or alliance?

Question

If a country wants to join an international organization or alliance, and that organization wants that country to join, then they're in as soon as they signed the papers or whatever ratifies that. But how can a country guarantee to not join?

For example, Russia has as one of its main demands in its current war with Ukraine, that Ukraine shall not join NATO. Let's assume the Ukrainian government finally agrees, they sign the peace treaty, the Russians go home, and then suddenly the Ukrainian government steps down or gets ousted in a coup, and the new government declares the treaty (made by the previous government they deem "traitorous") invalid, and joins NATO anyway before the Russians can react.

What measures can be done (or are usually done if it has been done before) to guarantee that the above "trick" cannot so easily void such an agreement?

_{Edit: of course nothing is 100% sure as there is no one to actually enforce such things between countries, but there surely can be measures to make it more binding. I doubt (for the example I used) that Russia will be satisfied with a simple "ok, sure, whatever", without any more complex agreements and guarantees. In the pre-modern eras it was usually done by exchanging family members of the royal families as hostages, but that practice died out a long time ago. So let's understand the question as how would it be made more difficult for such a treaty to be easily and trivially overridden?}

Answer 1

There is no way for them to guarantee this. Anything that they can do such as a law, treaty, or change the their constitution can also be undone at a later date. This would also include the organization/alliance adding rules about the country joining as they can be changed at a later date. Things like this are impossible to do as anything that can be done to prevent it can be undone.

Answer 2

A country that have violated one or more important agreements it has previously signed has no more trust. This later may block important negotiation paths for the violated side, as possibility to promise something expecting others will trust is the valuable asset.

For instance, a common argument against Ukraine just shedding the occupied territories and signing a peace agreement with Russia is that "We known they do not respect these agreements, they simply come again. They will just use time to rebuild the army". This blocks exit strategies that otherwise would maybe get more support over the world.

Obligation not to join some union would be the same agreement as any other.