Not that long ago, it seemed the world would never forget Neda Agha Soltan.
On June 20, 2009, a government thug fired a bullet through the 26-year-old's heart as she stood watching protests against the blatant election fraud that had secured victory for a presidential candidate backed by Iran's supreme leader, Ayatollah Ali Khamenei.
Video of her dying moments went viral, and Neda became a global symbol of the Green Revolution, as the Iranian people called their movement to topple a regime capable of such bloody deeds. "I think that anybody who sees it knows that there's something fundamentally unjust about that," President Obama said that week.
Today, Iran is once again in the headlines but not because Neda's murderers are about to be held accountable. Nor has there been fundamental change in the regime that jailed and killed many rank-and-file members of the Green Revolution and continues to confine the movement's leaders.
No, we're talking about the nuclear deal that the world's great powers, led by the United States, signed last weekend with Khamenei's representatives amid much smiling and backslapping. No one's talking about Neda.
Maybe we should be. Beyond the haggling over centrifuges and uraniumenrichment levels, the pact poses a dilemma that has haunted previous arms-control efforts: If a regime would defraud, imprison and murder its people, or support terrorism throughout its neighborhood, why would it hesitate to deceive and manipulate other nations in its pursuit of nuclear weapons? Even stating that dilemma is to question a basic premise of arms control and its first cousin, nonproliferation: that the nature of the regime across the bargaining table is less important than the fact that it has or wants nukes.
During the Cold War, Western critics of detente with the Soviet Union insisted that disarmament talks could not bring about durable peace with a communist empire bent on dictatorship at home and expansion abroad.
According to this view, embraced by the likes of Ronald Reagan and Margaret Thatcher -- and ridiculed by many a bien-pensant foreign-policy pundit -- regime change in Moscow was not only thinkable but necessary.
These cold warriors were realistic enough not to advocate regime change by force. But they were willing to stiffen Western nuclear defenses, maintain economic sanctions and talk straight about the immoral nature of Soviet rule, even when critics suggested that doing so threatened coexistence with a supposedly permanent adversary.
Reagan and Thatcher understood that the Soviet Union was both a geopolitical power and an ideological one that purported to offer a "progressive" alternative to democratic capitalism; vocal Western support for dissidents therefore attacked the regime at its weakest point.
The strategy bore fruit with the rise of Mikhail Gorbachev, a new kind of Soviet leader who was willing to renounce the system's old ways, both externally and internally. In a real sense, the Cold War ended because the West won it.
Today's hard nuclear cases, North Korea and Iran, are different. Both repress their people -- Pyongyang even more than Tehran -- but their ruling ideologies, Juche thought and Shiite Islam, respectively, lack global appeal or even the pretense thereof.
Their external ambitions are highly dangerous but focused on their own regions.
U.S. political will to wage a long struggle against them is accordingly weaker, and that probably would be the case even if Americans were not war-weary from Iraq and Afghanistan.
North Korea leveraged its pursuit of nuclear weapons to obtain its enemies' money, raw materials, diplomatic attention and, crucially, silence regarding the enslavement of its people.
Reluctant to risk war, the United States, Japan and South Korea have taken on a kind of "can't live with 'em, can't live without 'em" attitude toward the sinister Kim dynasty, beginning with the first -- never fulfilled -- arms-control deal signed two decades ago.
Syria's Bashar Assad probably seeks a similar outcome from his last-minute agreement to have international inspectors destroy his chemical weapons. And now the mullahs in Tehran, pressured by U.S.-led sanctions, may see the chance for their own modus vivendi with the United States.
Their endgame would not be Persian perestroika but endless discussion about Iran's nuclear capability, which would never be surrendered but would always be in play diplomatically -- the better to secure the gradual loosening of sanctions and to give U.S. diplomats plausible arguments to postpone the use of force by the United States or Israel.
With Iran's economy restored and its diplomatic legitimacy enhanced, the theocracy could vanquish its internal foes and, over time, increase its clout in Lebanon, Syria, Iraq and Shiite regions of the Gulf.
So much for the Green Revolution. So much for regime change. And so much for the memory of Neda Agha Soltan.
Charles Lane is a member of The Washington Post's editorial board.