Just musing, although I'd be surprised if several governments aren't thinking along these lines. Contact, individually and secretly, three or four of the top men in Putin's circle. Offer an amnesty from war crimes, a substantial amount of money, a new identity and somewhere safe and warm, in exchange for Putin, alive, delivered to the Hague. That sets off the thought "If Yuri does it, he'll get the reward, and I'll still be liable for war crimes". They can't confer among themselves, since they don't know who is going to tell Putin. See who breaks first.