"Great nations do not fight endless wars."

If there's one sentence that might endure from President Trump's 2019 State of the Union address, that's the one. It is a straightforward rebuke to the purveyors of the conventional wisdom in Washington, the sort of folks who imagine that earlier empires showed their greatness rather than their senescence by refusing ever to let go, and who like to quote Rudyard Kipling's famous poem without understanding what it actually prophesies.

I cite Kipling primarily because of Washington Post columnist Max Boot, who took the title of one of his most successful books from a line from that poem, and whose recent and instantly-infamous column explicitly called for America to stop worrying about winning and prepare to police the Middle East for decades or even centuries. He is the most unapologetic of Washington's neo-imperialists, and the most obvious target of Trump's apothegm, though he has plenty of company. But I cite him as well because a proper understanding of the poet of imperialism clarifies both the true source of its appeal, and why those most under its sway are so often reluctant to admit just what that appeal is.

What Kipling infamously called the "white man's burden" was a burden precisely because, in Kipling's view, it would not bring any benefits to the civilization that was called to empire. The empire's best and brightest would go abroad, and would die there after a lifetime serving other peoples' interests rather than their own. Those they governed would be be sullen at best, violently hostile at worst, and certainly never thankful for all they gained from beneficent imperial government. And at the end of the imperial road lies the fate described in the elegy he wrote for Queen Victoria's jubilee, "Recessional," the inevitable post-imperial twilight, Victoria eliding easily into Ozymandias.

Why take up the burden, then? Because the willingness to undertake that kind of sacrifice was the true measure of national greatness.

Of course, Kipling wasn't remotely accurate in describing either the effects or the intents of imperial rule. The people of India (or the Philippines, for that matter) had ample reason to hate their conquerors (the overt racism that Kipling vigorously shared being only the most obvious one), and the East India Company was assuredly not chartered for philanthropic reasons.

Nonetheless, Kipling got something of the imperial psychology right. The men who staffed the British Empire did feel they were doing something important. They were, in plenty of cases, willing to make substantial sacrifices, sometimes unto their lives. That remains true even if all they sacrificed for was that very sense of being part of something important.

Our contemporary advocates of American omnipresence share Kipling's delusions of high-mindedness, but they abjure his fatalism. Instead, what they typically say is that endlessly policing the world is necessary for our own security, that if we don't fight them there — whoever "they" are and wherever "there" is at any given moment — then we'll surely have to fight them here. America can't possibly be overextended because we enjoy nearly limitless resources and because shows of weakness cause adversaries to multiply.

There's a great deal of dishonesty behind these arguments, of course. In these cost/benefit calculations, there's rarely a willingness to treat sunk costs as truly sunk, nor to consider the downside risks of intervention along with the downside risks of inaction. There's also never any serious reckoning with the ways in which the interests of those who advocate and command our wars diverge from those who prosecute them. Least of all is there any reckoning with the risks to our republican institutions of institutionalizing endless war.

But somewhere behind these phony calculations is that same call to greatness. Great nations don't give up. If we ever stand aside, ever back away, ever say we've done enough or have no interest at stake, are we not admitting our own decline?

That's why I think Trump's phrase actually matters.

Greatness is Trump's watchword, his brand. If he says "great nations do not fight endless wars," then they don't — at least for those who, hearing the same thing from a politician from the left, might be most inclined to call withdrawal a stab in the back. But to say "great nations do not fight endless wars" also prompts the question: What do they do, then, those great nations, when faced with an intractable conflict?

Perhaps they quit while they're ahead. Perhaps they even quit while they are behind, declare victory anyway, and go home. Perhaps they care little for how such behavior looks because the people doing the looking are less great than they, and so their opinion matters less than their own.

In the theaters where Trump has seriously entertained withdrawal, in the face of massive resistance from his own administration and his party in Congress, there is a clear case to be made for such a response.

Afghanistan is America's longest war. It's also one in which we achieved our most concrete objective — killing Osama bin Laden — nearly eight years ago. We could have quit then, if we were willing to accept the return of the Taliban to power. Instead, we stayed, but if Trump gets his way we'll finally quit and accept the Taliban's return anyway, just as we accepted peace terms in Vietnam in 1973 that we had rejected years earlier.

The war against ISIS in Syria has never had any legal justification. Inasmuch as it had moral and geopolitical justification, it was that the group was so violent and fanatical that allowing it to gain a permanent territorial foothold — and access to substantial revenue — was to court far greater terrors down the road. Today, if the terrorist group is not yet completely wiped out, it is a pale shadow of its former self, and no justification for a permanent presence in the country. But America is not in Syria because we must continue fighting ISIS; rather, ISIS is the excuse that allows us to remain in Syria, so as to remain a player in a game of influence against Iran and Russia.

Finally, there is North Korea. Here, the United States achieved its first objective — saving South Korea from a North Korean invasion — in the 1950s, and its larger objective — holding the line against a repeat performance — with the collapse of the Soviet Union. A North Korean invasion would be suicidal even if there were no American troops in South Korea. The United States remains in South Korea substantially because that is a way to preserve our influence in the region, and the largest reason why North Korea will not give up its nuclear arsenal is precisely their fear of an American-led campaign for regime change. If Trump declares victory and goes home, whether or not North Korea fulfills its commitments to denuclearize, America's direct influence will surely be diminished. But will our greatness?

That's the question that Trump has put on the table, the most important question of his presidency. Trump has not been pursuing a foreign policy of restraint — far from it. Even as he seeks to withdraw from theaters like Afghanistan, Syria, and the Korean Peninsula, he has thrown American support behind Saudi Arabia's brutal war in Yemen, has proposed military intervention in Venezuela, and has laid the groundwork for military conflict with Iran. His policy is not so much "declare victory and come home" as "declare victory and move on."

What he has started to do is change the meaning of greatness, from "bear any burden, pay any price" to something more familiar from the business world. Business leaders are considered great for building impregnable fortresses of profit, and putting fear into the hearts of their competitors. Nobody ever called a CEO great for continuing to pour money into an unprofitable line of business, or for repeatedly entering businesses where he had no chance of competing. Why would we call nations great when they do the same?

Of course, from the Plaza Hotel to Atlantic City to his golf courses, Trump's career has been marked by precisely those kinds of poor business decisions; his own business greatness has always been a sham. So it's ironic that he's the man who is trying to transplant that notion of greatness into American geopolitics. But it would be a far bitterer irony for the country if his political opposition picked up the burden that Trump has begun to throw off simply out of a desire to deny him a win.