At the Democratic Party presidential debate held this month in Ohio, the candidates sparred over topics that have so far defined the campaign: impeachment, the economy, gun safety, immigration, education, income inequality, corruption, the opioid epidemic, and of course, “Medicare for All.”

However, during a debate that lasted nearly three hours, less than 15 minutes was spent tackling foreign policy issues. The only one discussed was President Donald Trump’s recent decision to withdraw American troops from northeastern Syria, effectively green-lighting a Turkish invasion that resulted in the betrayal of our closest allies in the war against the Islamic State, the Syrian Kurds.

This has not been unusual. The Democrats have held four primary debates this year, and while they have featured substantive conversations on healthcare, staggering job wages, and immigration policy, that has not extended to the numerous foreign policy crises the next president will face. And that is not due to a shortage of pressing international issues – the Trump administration has attacked our closest allies and has withdrawn from or threatened to withdraw the United States from NATO, the North American Free Trade Agreement, the Iran nuclear deal, the INF treaty, the Trans-Pacific Partnership, and the Paris Climate Accords. The president has launched a disastrous trade war with China that is damaging global economic growth and hurting consumers worldwide. He has failed to denuclearize the Korean Peninsula while conferring legitimacy on North Korea’s dictatorial ruler, Kim Jong-Un. And, to top it all off, Trump has botched repeated attempts to end the war in Afghanistan while nearly embroiling the US in another Middle Eastern war.

In other words, there are multiple avenues Democratic presidential candidates can take to attack Trump on foreign policy and draw meaningful contrasts with him, but they are missing valuable opportunities. The president has made America and the world less safe, but beyond vowing to end “endless wars” and withdraw American soldiers from Afghanistan and the Middle East, the 2020 Democrats hardly articulate that.

There is an old maxim in American politics that, “voters vote their pocketbooks,” or that voters look at the economy when choosing the president, but recent American history tells us otherwise. In past elections, candidates have successfully used foreign policy issues to attack the opposing party for endangering American national security. A look back on some of these elections tells us current Democrats should do the same.

Cold War tensions dominated the 1960 presidential campaign between Senator John F. Kennedy and Vice President Richard Nixon. Three years earlier, the Soviet Union (USSR), America’s chief geopolitical rival, launched Sputnik, the first human-made satellite, into orbit around Earth. The satellite’s launch unleashed a wave of fear and panic across the American public that the US had technologically fallen behind the Soviets. Two years later, the Cuban Revolution brought Fidel Castro to power, and by early 1960, he had firmly aligned himself with the USSR, raising alarms about a potential spread of communism in the Western Hemisphere. And, during the heat of the campaign, a CIA U-2 spy plane was shot down over Soviet territory and its pilot captured, causing a major international embarrassment for the United States and reinforcing fears America was vulnerable to Soviet attack. Public opinion polls at the time showed more than half of Americans thought war with the Soviet Union was “inevitable.”

Kennedy seized on this to attack incumbent President Dwight Eisenhower, and by extension, Nixon, as “soft” on communism and defense. His critiques were exemplified by his claims that the Republicans had allowed a “missile gap” to open up between the US and the USSR, and that the Soviets had an advantage in nuclear missile counts. Kennedy also repeatedly hammered Eisenhower for ignoring professional military officers, who warned that his administration’s reliance on nuclear weapons as a deterrent against a Soviet attack was a strategic mistake.

As Nixon struggled to respond to Kennedy’s attacks, Kennedy’s ability to paint striking contrasts with Nixon on foreign policy helped him narrowly carry the election. Kennedy promised to close the missile gap and regain superiority in the Cold War. It was a valuable lesson Nixon would remember during his second run for the White House.

Eight years later, Nixon ran for president again on a platform of restoring domestic stability and ending the Vietnam War. By 1968, America had been ripped apart by Vietnam, and a growing antiwar movement had led a majority of Americans to oppose the war. Nixon tapped into these sentiments by relentlessly attacking Democratic President Lyndon Johnson’s handling of the war, while the Democrats were bitterly divided between pro- and anti-Vietnam camps. Nixon was so convinced the war would help him win the presidency that he attempted to scuttle Johnson’s Vietnam peace talks days before the election. Nixon narrowly won, and it is clear his pledge to end the Vietnam War played a substantial role. Nixon learned from 1960 that using foreign policy issues in an election as a political tool can help lift you to victory.

During the 1980 campaign, Ronald Reagan pitched voters on two simple, interconnected promises: repairing American economic health and restoring American military strength vis-à-vis the Soviet Union. Reagan pledged to raise national defense spending, which a slim majority of Americans believed was too low. He denounced incumbent President Jimmy Carter’s foreign policy, claiming Carter had made America weak and that the country was being taken advantage of by its enemies. His criticisms were reinforced by daily television coverage of the Iran hostage crisis, which reminded Americans that Carter had failed to rescue 52 Americans being held prisoner in Tehran after anti-American students stormed the US Embassy there. The hostage crisis, combined with the Soviet invasion of Afghanistan, a weak economy, and American perceptions that its nation was in decline, contributed to Reagan’s landslide victory over Carter.

In the twenty-first century, foreign policy has continued to play a major role in presidential campaigns. The 2004 election was a referendum on President George W. Bush’s “War on Terrorism” and his decision to invade Iraq. According to election exit polls, 34 percent of respondents said either the Iraq War or terrorism were their top concerns followed by the economy at 20 percent. Four years later, Barack Obama made ending the Iraq War one of his core promises if he was elected President, and his critiques of Bush’s approach to foreign policy was a staple of his stump speech. In the last election, Trump pledged to end endless wars and remove American forces from Afghanistan and the Middle East, which strongly resonated with voters fatigued with overseas military adventures.

Now, it is the Democrats’ chance to turn the foreign policy tables on Trump. His foreign policy (or lack of foreign policy is more precise) has left America isolated and vulnerable. He has squandered American leadership and retreated from the world, leaving hostile powers to benefit from our missing presence. Recent presidential elections have shown that effective foreign policy critiques can help persuade voters to shift course, and Trump has given Democrats no shortage of ammunition. They would be wise to take advantage of it.

Grant Golub is a PhD candidate in International History at LSE. His research focuses on American foreign relations and diplomatic history. He holds a BA in History and American Studies from Princeton University and an MSc in History of International Relations from LSE.