It would have to be USA-led... you know that.
The UK (Britain actually) was also a party to the Budapest Memorandum so they also should have troops included.
Aside from those two, it doesn't matter anymore. But Poland, Czechia, Slovakia and Romania would have direct interest as well in participating in the stabilization of Ukraine.
It could even start slowly, with the US putting NASAMS and other anti-aircraft/ missile defense teams in first. Followed by air support and then combat troops. Start in the west and up to the Dnieper River... wait to see if Ukrainian troops secure the entire western half of Ukraine at least up to the Dnieper (Kherson included), and start from there.
Simply inserting ANY troops/ other into Ukraine will rush Putin to the table to make certain he can keep Crimea. He wants the land bridge... but above all else he MUST be able to keep Crimea.