> Ukraine gave up their nuclear weapons

Ukraine never had nuclear weapons. Russia is the sole legal successor of the USSR and these were all Russian nukes on Ukrainian territory.

> in exchange for peace from Russia

There isn't a single mention of nuclear weapons in the Budapest Memorandum.

> Ukraine never had nuclear weapons. Russia is the sole legal successor of the USSR and these were all Russian nukes on Ukrainian territory.

Structuring the breakup so that the nukes are Russia's is not really different than Ukraine giving up the nukes on its territory.

Where did they draw the line? Obviously not all USSR assets are now Russian assets, as Ukraine still has (or had) its own stockpile of Soviet era weapons, and other things like Soviet era airfields.

> There isn't a single mention of nuclear weapons in the Budapest Memorandum.

https://web.archive.org/web/20170312052208/http://www.cfr.or...

Points 4 and 5 mention and are about use of nuclear weapons.

I think the memorandum was intended to be a security guarantee to Ukraine after they (and Belarus, and Kazakhstan) joined the NPT and transferred formerly-Soviet nuclear weapons to the Russian Federation. I don't know why anyone would suggest otherwise.

This is over simplified to the point of being misleading/wrong. Russia was the legal successor of the USSR for purposes of diplomatic continuity, but the other Soviet successor states divided portions of the Soviet military/equipment, split Soviet debt obligations, etc on a case by case basis.