By most scholarly rankings, Jimmy Carter, the 39th president, was far from one of America’s finest. He served a troubled single term from 1977 to 1981, marked by “malaise” and crisis after crisis that left Americans wondering what sort of future lay ahead for a country that had just celebrated its bicentennial.

Yet it was also Carter who, on the night of January 23, 1980, delivered the State of the Union address that forever changed the course of United States foreign policy and set the stage for much of what was to come in the succeeding decades. In fact, its impact can still be felt today, 40 years later.

Carter’s third and final State of the Union came at a particularly troubled time, which gave it a sense of urgency. Just two months earlier, the Iranian Revolution had resulted in the siege of the U.S. embassy in Tehran, with 52 Americans held hostage. Just over a month later, the Soviet Union invaded Afghanistan, capping off 1979 with a sense that the U.S. was losing control over global affairs. Meanwhile, Carter presided over slow economic growth, coupled with inflation and high unemployment (“stagflation”)—a problem exacerbated by high oil prices, which were elevated in part by the situation in Iran. Topping it all off was an election in November, with Carter’s re-election very much not a done deal.

This was the backdrop against which Carter delivered the most important address of his presidency. With the wife of Bruce Laingen, the senior-most diplomat held hostage, in attendance, the president uttered the proclamation that came to be known as the “Carter Doctrine”: “Let our position be absolutely clear: an attempt by any outside force to gain control of the Persian Gulf region will be regarded as an assault on the vital interests of the United States of America, and such an assault will be repelled by any means necessary, including military force.”

The Carter Doctrine was largely the brainchild of the president’s realist national security advisor Zbigniew Brzezinski. As Brzezinski recalled in his memoir: “The [Carter Doctrine] represented a formal recognition of a centrally important reality: that America’s security had become interdependent with the security of three central and inter-related strategic zones consisting of Western Europe, the Far East, and the Middle East-Persian Gulf area.”

While instability in countries like Iran and Saudi Arabia were troubling on their own, Carter’s use of the term “outside force” made clear that the Soviet invasion of Afghanistan was the catalyst for policy change. After a period of détente, it seemed as though the Red Menace was on the march and was now seeking control of Mideast oil fields. With the president’s declaration, the Persian Gulf was officially an arena of superpower conflict.

In truth, it had been for decades. It was under President Franklin Roosevelt in 1945 that America’s enduring and controversial relationship with Saudi Arabia was formally established. Every successive administration had to tackle a Middle East crisis, with the common thread being the containment of Soviet expansionism. And it was Dwight Eisenhower who established a precedent of military intervention in the Middle East to counter Soviet advances, particularly following the 1956 Suez Crisis and decline of Britain and France as the guarantors of peace and stability in the region

When Britain withdrew from the east of Suez in 1971, it all but christened the U.S. as the new policeman of the region. Richard Nixon opted to balance Iran and Saudi Arabia against each other to ensure stability, while selling vast quantities of arms to Tehran as a bulwark against the Soviet Union, which lay right over Iran’s northern border. The 1973 Yom Kippur War resulted in a months-long oil embargo by Arab petroleum producers and other countries supporting Israel’s war effort, which contributed to an American recession and included a brief yet unsettling confrontation with the Soviets. These events further led Nixon to consider the possibility of military intervention in the region.

As early as 1977, the military took planning for a Middle East contingency more seriously. President Carter approved the creation of a highly mobile strike force that could respond to crises anywhere on short notice; this was the genesis of the Rapid Deployment Joint Task Force (RDJTF). As the situation in Iran deteriorated and Moscow showed signs of making big moves, plans were developed and forces allocated long before the embassy seizure and the invasion of Afghanistan.

RDJTF was finally stood up on March 1, 1980, and on January 1, 1983, became Central Command (CENTCOM). Its focus over its first few years was on blunting a Soviet invasion; that would later shift during the Reagan administration. As relations improved with a declining Soviet Union and the Iran-Iraq War raged on with no end in sight, CENTCOM’s activities took on a more limited, regional scope, both in planning and in practice. From 1987 to 1988, the U.S. escorted oil tankers through the Persian Gulf to protect them from attack by Iran. In 1988, there were several naval skirmishes in the Gulf, with the U.S. destroying half the Iranian naval fleet in Operation Praying Mantis. 

Then in August 1990, long after the Iran-Iraq War had ended, Saddam Hussein ordered the annexation of Kuwait. The then-10-year-old Carter Doctrine, coupled with the shift towards ensuring regional stability, compelled the George H.W. Bush administration to intervene, initially to defend Saudi Arabia from further Iraqi aggression. Codenamed Operation Desert Shield, it became Desert Storm on January 17, 1991, and resulted in the liberation of Kuwait at the end of February. And here we arrive at the most enduring consequence of the Carter Doctrine—a nearly 30-year-old military commitment to Baghdad with no end in sight. From 1991 to 2003, the U.S. and its allies enforced no-fly zones and an economic embargo on Iraq, culminating in an invasion of the country in March 2003 to terminate Saddam Hussein’s regime once and for all. A controversial military occupation ensued, as American troops battled a hideous insurgency and struggled to hold the country together.

After the Obama administration achieved a “decent interval” following withdrawal in December 2011, the scourge of the Islamic State forced their hand and U.S. troops and warplanes were back in Iraq beginning in June 2014. Even after dealing ISIS significant defeats, the U.S. has maintained its foothold to prevent a resurgence. Mission creep has also given a new mission to American forces—countering Iran. It’s one that’s brought both countries closer to a hot war.

Even the 18-year effort in Afghanistan can be traced back to the Carter Doctrine. Convinced the Soviets presented a clear and present danger to global oil supplies, Carter authorized the arming, funding, and training of the Afghan mujahideen fighting a guerrilla war. This program, Operation Cyclone, was expanded under Reagan and viewed as contributing to the Soviet failure to achieve victory.

But it arguably had the effect of strengthening the very forces in Afghanistan that would later form the Taliban regime, which would harbor Osama bin Laden and al-Qaeda. Beginning in late-2001, the U.S. sought more than vengeance for 9/11— policymakers attempted to remake the country to save it from falling under similarly malign influences. Two decades later, America is expending more ordnance than ever in Afghanistan, 13,000 troops remain in-country, and an exit appears as elusive as ever.

How does Jimmy Carter reflect upon his role in changing the trajectory of American history? In a 2016 interview, he insisted that his 1980 State of the Union deterred Soviet leader Leonid Brezhnev from going any further than Afghanistan. Strategic and operational considerations made the likelihood of a Soviet seizure of Gulf oil fields minimal and evidence that Moscow had designs on the region was scant. In fact, threatening Brezhnev with military force likely wasn’t what prevented a Soviet invasion of the Persian Gulf.

On more than one occasion, Carter referred to the Afghan mujahedeen as “freedom fighters” and expressed no regrets over aiding them. Yet hindsight being 20/20, there’s no way around the fact that yesterday’s freedom fighters became today’s terrorists, a threat the U.S. just can’t seem to extinguish.

Back in 1980, Carter’s speech was well received by the public and the media, though he’d ultimately lose the election to Reagan in November. In many ways, it was what the country and the world needed to hear at the time. But its long-term impact has been undeniable. The Carter Doctrine undeniably made the Middle East the focal point of U.S. foreign policy in the years to come and progressively introduced a military presence that at times would number in the hundreds of thousands. It constitutes tens of thousands today.

Such is the power of policy made official in a momentous speech like the State of the Union. President Carter may have served only one term, but 40 years ago he helped create a world that we’re all still living in.

Edward Chang is a defense, military, and foreign policy writer. His writing has appeared in The American Conservative, The Federalist, The National Interest, and War Is Boring. He can be followed on Twitter at @Edward_Chang_8.