Editor's note: An earlier version of this column ran with a cartoon which inaccurately stated the name of the cartoonist. The correct cartoonist is Connor Murphy. 

In the world of international politics, allies and adversaries seem static for long periods of time, but then they shift quickly and decisively. American relations with Russia are an excellent example of this phenomenon. The countries were Cold War enemies in the 1980s, strategic partners in the 1990s, and now they are antagonists again. Iraq is another prime example. In the 1980s Iraqi dictator Saddam Hussein was an American ally, in the 1990s he became a strategic threat, and in 2003 Americans labeled him an enemy in the “Global War on Terror.” Britain’s great nineteenth century prime minister, Lord Palmerston, put it best when he observed that countries do not have permanent allies or adversaries, only permanent interests.

During the 1970s, Iran was one of the United States’ most important allies in the Middle East. Under Shah Mohammad Reza Pahlavi’s dictatorship, the government in Tehran used its vast oil wealth to build a modern state that imported technology from abroad and contained both communism and Islamism in the region. The United States, Israel and Saudi Arabia worked closely with Iran to protect the flow of oil and maintain political stability.

When the Islamic Revolution in Iran overthrew the Shah in 1979 and held 52 Americans hostage for 444 days, the United States and Tehran became mortal enemies. Iran’s new leader, the Ayatollah Kohmeini, called America the “Great Satan.” Presidents Jimmy Carter and Ronald Reagan labeled Iran a “terrorist state” and they worked to overthrow the regime. Carter and Reagan also negotiated with the Iranian government when they felt the regime could facilitate the release of American hostages in Tehran and other parts of the Middle East. These negotiations, however, did not reduce the enmity between Washington and Tehran.

Iran’s effort to develop nuclear power, and an accompanying weapons capability, crossed both periods, before and after the 1979 revolution. Encouraged by the United States, the Shah used his wealth to purchase capabilities and resources from foreign suppliers, including France, Germany and the United States. Cut off from many of these suppliers after 1979, the Islamic government turned to other sources, including the illegal network run by Pakistani scientist A.Q. Khan. During the two periods Iran’s partners changed dramatically, but its nuclear ambitions remained consistent.

This often neglected history brings us to the current moment in relations between the United States and Iran. Years of sanctions and isolation have taken their toll on an Iranian society that struggles to access foreign supplies and technology. Internally, citizens have shown frustration with an Islamic regime that is unable to deliver an improved standard of living for its growing population. The Arab Spring began in Iran in 2009 with street protests against an election stolen by the Islamic leaders. In 2013, Iranians elected a foreign-educated president who promised reforms and an opening to the West, despite the continued domination of religious mullahs in the country’s politics.

The United States remains firmly committed to both the denuclearization of the Islamic government in Iran and democratic reforms. As it negotiates for these goals, Washington has found itself cooperating, at least informally, with the Iranians on a number of common strategic challenges. In Iraq and Syria, the United States and Iran share a strong interest in defeating the radical Sunni Islamic State. Washington and Tehran have shared intelligence and cooperated on the battlefield. The United States and Iran both support the new Shiite government in Iraq, and they are both training the new Iraqi military. Of course, the two countries are on different sides in the Israeli-Palestinian conflict, and Iran continues to support Syrian leader Bashar al-Assad; but in the struggle for Middle East stability, Washington and Tehran find themselves frequently working together. 

The current negotiations between the United States and Iran on nuclear non-proliferation and economic sanctions reflect these circumstances. After months of intensive discussions, the two sides seem so close to agreement. Iran needs international trade and Washington is keen to offer that. Washington is determined to prevent an Iranian nuclear bomb, and many in Tehran seem to recognize that a nuclear capability is not worth the overwhelming costs. 

What keeps the two sides apart is something other than the details, but a bigger question of trust. Can Washington and Tehran find a way to trust one another? Trust does not come overnight. It requires a sustained relationship, consistent goals and clear expectations. More than anything, it requires the personal outreach of leaders who are willing to put themselves on the line.

After more than 30 years of hostility, relations between the United States and Iran can and will shift when the leaders of these two powerful states commit to work together. Such a commitment will make the details fall into the place and the common interests rise above all else. To insure that outcome, we must maintain our toughness but also reach out. Americans want better relations with Iran, and we must show that, as we also show that we will not tolerate the extremism that brought us to conflict in the first place.   

Suri is a professor in the Department of History and the LBJ School of Public Affairs.