The last time that we invited outsiders to participate in a purely American dispute was back in the Civil War, when the Confederacy went begging to Great Britain to intervene on its behalf. Now it seems that we're at it again, and it leaves me both flummoxed and deeply worried.

In this case, the outsider is Russia. Confronted by overwhelming, documented evidence that the Trump campaign at least attempted to enlist the Russian government into its cause, defenders of President Trump have retreated into an argument that amounts to "so what if they did?"

There are a lot of ways to answer that. The pragmatic response would be to point out that if you take ill-gotten information from Vladimir Putin and use it in your campaign, congratulations: You just became Putin's pawn. With the push of a send button to his pals at Wikileaks, he can now destroy you at the moment of his choosing, and he knows it and you know it.

Another way is to point out that if this identical scandal were playing out under a Democratic president, with Russian interference not just welcomed, but rewarded and encouraged with Russia-friendly policies, the GOP response would be dramatically different. Fox News would be beside itself, unleashing the furies, and the gears of impeachment would be well-oiled and turning. And while we cannot say for sure, I just don't think that Democrats as a whole would be rushing to defend such behavior or trying to explain that while it looks bad to turn to Russia for election assistance, it's not illegal or criminal so it must be OK.

I just don't think that would happen.

But here's what has me gut-sick: Healthy nations don't do this. Americans don't do this. We don't invite outsiders to take part in our fights, to help us in our battles with fellow Americans. Elections are fought and settled here, right here, within the family.  It's about us, not them. If our battles with each other have become so heated that it is now acceptable to call in third parties to help our side win -- third parties that have historically been our nation's adversaries -- then we have lost something critically important.

That transformation is all the more startling because it comes from a party and president that in every other context claims to be deeply nationalistic. "America First," as the slogan goes.

According to them, we need The Wall to preserve the sanctity of our border. We need ever more stringent election laws to ensure that only American citizens are allowed to vote, to guard against even the small possibility that some illegal immigrant somewhere in this country might violate the purity of the ballot box. We also want no restrictions placed on us by international agreements that might impinge on our national sovereignty, and immigration bans and trade barriers are the executive order of the day.

"We want to build with American workers, and with American iron, aluminum and steel....Buy American, and hire American," as President Trump recently put it. "We have sent a clear message to the world that we will not allow other nations to take advantage of us any longer."

Yet somehow, when it comes to outsourcing of opposition research to the intelligence agencies of foreign adversaries, it's stunning to see that obsessive concern for national sovereignty just evaporate. If an immigrant dares to vote illegally, we sentence her to eight years in prison, but if an entire country picks a side in our election and actively tries to intervene, we're told it's no big deal.

If that's OK, what isn't OK? What's left?