I thought of Shirreff’s scenario again on Wednesday, when Trump expressed a degree of tolerance for Russian land grabs by suggesting in a press conference that he might, as president, recognize Crimea as Russian territory.

I was curious how Shirreff envisioned his plot unfolding with President Trump leading the United States rather than the fictional President Lynn Turner Dillon, a “tough businesswoman” with “highlighted blonde hair” who Shirreff insists is not modeled on Hillary Clinton (or a Clinton-Trump hybrid, for that matter). On the one hand, Trump, like Shirreff, is trying to pressure European NATO members to spend more money on defense and rely less on America’s military might. On the other hand, Trump is expressing the very reluctance to defend fellow NATO members that so frightens Shirreff. I was also curious whether Shirreff felt Trump’s position on NATO was as radical and reckless as Trump’s critics claim.

“NATO depends totally on American leadership and American willingness to come to the aid of allies unconditionally,” he told me. “Therefore, to have a president in the White House who is not necessarily prepared to do that weakens the alliance immeasurably and may well lead to [the] decoupling of America from European defense.” Such an outcome, he argued, is bad not only for Europe, but also for America. As NATO Secretary General‎ Jens Stoltenberg put it following the publication of Trump’s comments, “Two world wars have shown that peace in Europe is also important for the security of the United States.”

But are NATO members really obligated to help each other unconditionally? I pointed out that Article 5 of the NATO treaty stipulates that if an “armed attack” occurs against a NATO nation, each member will assist the assaulted party by taking “such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area.” The Times asked Trump whether he would immediately offer military aid, and he declined to specify exactly what he would do if the country in question hadn’t paid its bills. Doesn’t the NATO treaty grant him some latitude on how to respond?

Shirreff urged me to focus on the clause about restoring North Atlantic security, not the line about taking whatever action is needed. If Russia were to occupy the territory of a NATO member, “then, clearly, armed intervention [by NATO] may become necessary,” he said. He added that unconditional support is the bedrock of NATO: It’s “the blank check that says, ‘If you get attacked, whatever happens, we’re going to come to your aid.’ ... As soon as you get into a sort of transactional approach, that completely undermines the strength of collective defense.”

Donald Trump, however, thinks transactionally—more so than any U.S. presidential aspirant in recent memory. And when you think that way, it’s hard to justify many features of the international system that the U.S. helped design after World War II. Those features are easier to justify when you consider America’s long-term economic and security interests. “We want allies to keep the peace, fight alongside us in times of war and defend our common values,” Michael McFaul, the former U.S. ambassador to Russia, recently explained in The Washington Post. “[F]ueling uncertainty about our security commitment to NATO in order to get the Latvians or Slovenians to increase their military budgets by a percentage point is not strategic.”