This post contains spoilers through the most recent episode of Game of Thrones, “The Spoils of War.”

It’s no secret that dragons have a deeper meaning on Game of Thrones. George R.R. Martin has specifically referred to them as “the nuclear deterrent.” Timothy Westmyer, a former research and program assistant at George Washington University, has argued in the Bulletin of the Atomic Scientists that dragons are “living, fire-breathing metaphors for nuclear weapons,” and that the series is deliberate in using dragons as a warning about the “inherent dangers” and the responsibility that comes with possessing and wielding such power.

But in the most recent episode of the HBO show, “The Spoils of War,” Game of Thrones offered its most explicit portrayal yet of the carnage dragons can cause. In the episode’s climactic final sequence, Daenerys accompanied the Dothraki in a two-pronged attack on the Lannister and Tarly armies, flying Drogon over the troops and incinerating their supplies (and most of their soldiers). The resulting damage was graphic, and instantaneous. Some men were reduced to ashes in seconds, while others burned to death more slowly, screaming in agony. One soldier writhed in pain while the skin seemed to peel off his face. Both Jaime and Tyrion Lannister, watching from different vantage points, were visibly horrified by the spectacle.

Which is the whole point. Daenerys has weapons that should, by rights, make her the most powerful person in the Seven Kingdoms. But she’s hampered, ironically, by the fact that her dragons are so exponentially more dangerous than any other force on the show. (Wildfire, which both Tyrion and Cersei have deployed in the past, and which has similarly gruesome results, is notoriously unstable and hard to control. It’s been likened in the past to napalm, which the U.S. infamously deployed in the Vietnam War, and which was outlawed by the United Nations in 1980.)

Dragons, like nukes, have the capacity to inflict maximum casualties with minimal effort—something President Harry Truman described as “a rain of ruin from the air, the like of which has never been seen on this earth.” But the cost of such weapons is that they’re so effective they can almost never be used. As Jon Snow said to Dany before she set off with Drogon, she’s gathered her armies by wielding compassion, not brute force. If she uses her dragons “to melt castles and burn cities,” she’s no different from any other power-hungry zealot, and she sacrifices the ethical compass—the soft power—that’s gotten her this far.

That doesn’t mean she’s afraid to deploy them in battle, as was proved in “The Spoils of War.” And if Jaime survives, his account of witnessing dragons in action will bolster how seriously the Lannisters take Daenerys as an enemy. But there’s another topical aspect to the catch-22 of her nuclear option. Possessing such powerful weapons only works as a deterrent to war if your enemies are similarly appalled by the cost of using them, and Cersei in particular seems unlikely to shed tears for civilians. As Westmyer writes,

Optimists who welcome nuclear weapons as a stabilizing influence insist that by their very nature, these arms cause rational leaders of stable regimes to maintain strict control over their state’s arsenals and moderate their behavior—or risk retaliation. That prompts the question: What happens when nuclear weapons are in the hands of irrational leaders, less than stable countries, or non-state actors? Fortunately for Westeros, its “Mad King” had no dragons at his disposal. “Burn them all,” he snarled while ordering his city be set ablaze rather than surrender—showing how retaliatory threats mean little to someone bent on suicidal violence.

In other words, both dragons and nuclear weapons offer the ability to inflict near-total obliteration, and as such they become weapons that are extremely hard to wield. Mark Bowden, in his July/August Atlantic cover story on North Korea, wrote that “there are no good options” when you’re dealing with the threat of nuclear warfare. Daenerys, like the United States, has the ability to destroy everything and everyone that stands between her and power, but if her ultimate goal is peace, burning down the Seven Kingdoms isn’t an ideal tactic.

As Martin said in 2011, the Dragon Queen is the only person in Westeros who has the nuclear option at her disposal, but that doesn’t make her omnipotent. “Power is more subtle than that,” he explained. “You can have the power to destroy, but it doesn’t give you the power to reform, or improve, or build.” To co-opt the title of my colleagues’ Game of Thrones roundtable this week, what’s the upside in being queen of the ashes?