I don't think the US should offer concessions. I suspect those won't help at this point. I think the US should offer clearly negotiated trades. Tit for tat, and no more. I also think the US should be very careful to stick to the agreements thusly made, because it could shut down possibilities for further negotiation and compromise. I think the US should walk into negotiations with Russia with a clear understanding of what Russia wants, and what they're prepared to offer, vs. what costs they're willing to incur in a confrontation with Russia if negotiations don't work out. In my opinion a purely pragmatic approach is best, with the understanding that offers need to be something tangible, and threats are basically useless. If the US is prepared to act, it should act.