What an illuminating interview Senator Cotton has given Jeffrey Goldberg of the Atlantic. It is the best we’ve seen with the junior senator from Arkansas, who leapt into the headlines by writing the letter that smoked out the Iranian mullahs into disclosing their game plan of cornering America at the United Nations. In his conversation with Mr. Goldberg, himself a brilliant interlocutor, the senator makes clear why he’s viewed as such a rising star.

Mr. Cotton started with Desert Fox, which strikes us as a canny point. It was the campaign in which President Clinton threw Tomahawks and used B-1 bombers against Saddam Hussein’s regime in Iraq, all in support of United Nations resolutions in respect of the tyrant’s sanctions violations. The senator is uncowed by the possibility of an asymmetrical response — Hezbollah, say, or an attack on us or our allies at the Gulf.

The senator characterized President Obama as “his own worst witness” against a military response to Iran. He noted the “almost mocking terms” the president used in marking the fact that we have a military budget that is, at $600 billion, 20 times Iran’s. It has given us the “capability, along with our Gulf allies, who have increased their military spending by over 50 percent, to largely protect them from any kind of retaliatory air or naval strikes.”

When Mr. Goldberg asked the senator whether he would prefer not to be engaged in this negotiation at all, Mr. Cotton pointed out that he had been among the 400 — i.e., heavily bipartisan majority — members of the House who two years ago voted for stronger sanctions. He said he “wouldn’t have started down this course of granting concessions to Iran, giving them billions of dollars when in return all we’re getting is their willingness to sit at the table.”

The Arkansan had no apologies for his letter to the mullahs. Mr. Goldberg inquired whether Mr. Cotton had asked himself, “Maybe I am undermining the executive branch?” Mr. Cotton pointed out that he was just marking the Constitution. He was generous to Mr. Obama in not pointing out that the president is treating with the mullahs via a state secretary whose career was launched when he met in Paris with Vietnamese Communists at a time when they had troops in action against our GIs. And then returned to echo their negotiating points.

In any event, the senator went on to argue that Americans are opposed not to war but to “losing wars.” Mr. Goldberg asked: “Do we have to win wars quickly to make them popular?” Said the Senator: “I don’t think we have to win quickly necessarily, but we have to win.” Which, he pointed out, we’d done by 2008. He reckoned Americans would have supported a decision to keep a residual force in Iraq. In any event, he calls the President’s formulation — “this deal or war” —a false choice.

The senator’s fidelity to the Iraq war resonates for us and, we’d guess, for others who are galled that Iraq is, after Vietnam, the second war in their lifetime that America abandoned after winning on the battlefield. Mr. Cotton also comprehends the relevance of the 1930, at which Mr. Goldberg was taken aback. “Wait, is this the 1930s to you?” Replied Mr. Cotton: “It’s unfair to Neville Chamberlain to compare him to Barack Obama.”

After all, he pointed out, Chamberlain’s general staff “was telling him he couldn’t confront Hitler and even fight to a draw — certainly not defeat the German military — until probably 1941 or 1942. He was operating from a position of weakness.” When we negotiated with Iran, he said, it was from “a position of strength.” He disputes entirely the notion that, say, President Rouhani is a moderate.

Mr. Cotton’s main strategic point is that the deal Mr. Obama is proposing would lead to a nuclear confrontation a decade or two off. “So your feeling is, deal with the problem now, before it gets worse?” the Atlantic legman asks. Replies Mr. Cotton: “In security matters, this is almost always the case,” adding that the world probably wishes that Britain had rebuilt its defenses and stopped Hitler from reoccupying the Rhineland in 1936.

Concludes he: “When President Obama likes to say, ‘It’s this deal or war,’ I would dispute that and say, ‘It’s this deal or a better deal through stronger sanctions and further confrontation with [Iran’s] ambitions and aggression in the region.’ And if it is military action, I would say it’s more like Operation Desert Fox or the tanker war of the 1980s than it is World War II. In the end, I think if we choose to go down the path of this deal, it is likely that we could be facing nuclear war.”