IN JANUARY 2015, as Islamic State militants were waging an offensive across Iraq and Syria, an Iranian intelligence officer known among his colleagues by the code name Boroujerdi sat down for a meeting with an important official: then-Iraqi Prime Minister Haider al-Abadi.

The meeting, held at Abadi’s office in Iraq’s presidential palace in Baghdad, took place “without the presence of a secretary or a third person,” according to a report about the discussion contained in a leaked archive of cables from Iran’s shadowy Ministry of Intelligence and Security.

Abadi was a member of Iraq’s exiled political class, mostly Shia, who had returned to take power following the U.S. invasion. The two men discussed a range of topics, including the threat of ISIS to the Iraqi state, the role of foreign powers like Turkey and Saudi Arabia in the region, and, finally, the position of the West. On at least one point, they agreed: Despite the threat of ISIS and other regional powers, the political conditions wrought by the U.S. invasion of Iraq and removal of Saddam Hussein had created an opportunity for the Islamic Republic of Iran and its allied Iraqi elites to “take advantage of this situation,” according to the Ministry of Intelligence and Security report.

Twenty years after U.S. troops first invaded Iraq, the classified Iranian intelligence documents, which were leaked to The Intercept and first reported in a series of stories that were published beginning in 2019, shed light on the important question of who actually won the war. One victor emerges clearly from the hundreds of pages of classified documents: Iran.