I suggest offering him California, New Jersey, Massachusetts, Washington DC, Chicago, New York City (or just lump it in with NJ), and any other statist garbage heap that insists on enforcing anti-gun legislation.
The offer will drop any of those places that suddenly decide to recognize the natural human rights of those who live (or travel through) there, but it will replace them with any city or state that proposes new anti-liberty rules during the negotiation or within a century of the agreement.
It's a win/win. Putin gets new territory and America takes out the trash, making the remaining population more free and stronger.