We are not obligated to abide by this law. The senate will not ratify this by 2/3, and the states will not abide by any law infringing on their sovereignty. If the UN wants to start a war with American people, they’re going to get it.
There's likely a pile of "laws" we are not obliged to abide by. Yet we do - day-after-day. Hopefully this latest assault will be the one that wakens the "Freedom gene" that the Founders had and this trend turns around. Unlike the other side, our side tends to be way to pragmatic (It may be wrong, but the law is the law and a nation without laws is...) and the other side has no compunctions about breaking any law that stands in their way.