“We’re eyeball to eyeball, and I think the other fellow just blinked.” — Secretary of State Dean Rusk in 1962 during the Cuban missile crisis.

In his address to the nation Wednesday, President Trump backed away from potential war with Iran. Instead, in a letter to the United Nations, the United States signaled that it was willing to enter “serious negotiations” without preconditions.

By taking the off-ramp, Trump triggered a tentative sigh of collective relief from those anxious about continued conflict in the Middle East. But recent research suggests that this apparent de-escalation in an election year should come as no surprise.

Presidents have incentives to avoid conflict in an election year

As my recent article in the journal International Security discusses, elections powerfully constrain presidential decisions about war and peace. As both commander in chief and holder of the highest elected U.S. office, presidents balance the competing interests of national security and political survival. When considering the use of force, they want any course of action they choose to carry minimal electoral risk.

Since voters bear the financial and human costs of war, they don’t usually reward incumbents who enter wars recklessly. As a result, presidents have good political reasons to think twice before putting troops in harm’s way. As President George W. Bush once joked to troops in the Middle East: “You don’t run for office in a democracy and say, ‘Please vote for me, I promise you war.’ ”

How strong this democratic constraint may be can vary across contexts and over time. But mounting casualties tend to erode public support for military engagements. As a result, policymakers usually worry about sustained conflict overseas, particularly if it involves boots on the ground.

My research shows that these dynamics were clearly at play during the Iraq War. As elections neared, the administrations of George W. Bush and Barack Obama grew increasingly anxious about additional or extended troop deployments. More broadly, a number of studies find that leaders facing reelection tend to be more conflict-averse, entering fewer wars in the months before an election than during other parts of their tenure.

Many have speculated that Trump tried to “wag the dog” — i.e., start a war to help get reelected — with the drone strike that killed Iranian Maj. Gen. Qasem Soleimani. But research suggests that approach is the exception, not the rule. As Michael Tesler argued earlier this week in a Monkey Cage article, Trump won’t get much of a boost from rally-around-the-flag sentiment, either in public opinion or at the polls. The president may have thought killing Soleimani would be politically popular and backed off when he got it wrong. Or it may have been an attempt to divert media attention from the politically damaging impeachment process.

Either way, Trump has apparently decided to de-escalate. That fits well with what we know about elections and war. Shows of “toughness” aside, the past shows that presidents have limited appetite for any sustained conflict in an election year.

Obama faced similar pressures about the Iraq conflict in 2011

When he was president in 2011, Obama decided to withdraw all U.S. forces from Iraq. That decision contradicted the broad consensus within his administration that it was strategically necessary to leave troops there to continue training Iraqi security forces and support counterterrorism operations aiming to prevent the resurgence of al-Qaeda branch in Iraq, which would later merge into the Islamic State group.

Why? Drawing on interviews with senior officials, my research shows that Obama was under increasing pressure to deliver on his 2008 campaign pledge to end what he once called a “dumb war.” In internal deliberations, the military kept offering — and the White House kept rejecting — proposals for a follow-on force, shrinking the size as the 2012 campaign season drew closer.

As president, Donald Trump touted that Iranians no longer chant “Death to America.” Then an Iran-backed militia stormed a U.S. Embassy shouting exactly that. (The Washington Post)

Finally, in October 2011, Obama abandoned efforts to negotiate an agreement with Iraq for a continued U.S. presence. Administration officials insisted that the Iraqi parliament was unlikely to provide support for a deal. But any agreement could have been approved by other means, without confronting parliament. And so, as former undersecretary of defense Michèle Flournoy told me, “that ended up being an excuse, or a public explanation, for what I believe was a policy choice.”

So what really drove the decision to withdraw all U.S. forces? Mike Mullen, former chairman of the Joint Chiefs of Staff, told me: “It was very clear. You go back to his campaign promise, and it was going to be zero. It’s just this question of how we were going to get there.”

Former CIA director John Brennan recalled: “Throughout this process, [Obama] was weighing a number of factors and considerations, not just in terms of security requirements but also some of those political dimensions as it got closer to the elections.”

Presidents want to be reelected. That affects their decisions about the use of military force.

For the U.S. presence in Iraq, it could be back to the future

Like Obama, Trump has made no secret that he wants to run for reelection having fulfilled his campaign promises to end the “endless” U.S. wars in the Middle East. Most recently, he justified his decision to withdraw troops from Syria in precisely those terms.

Recently, a senior U.S. commander sent a letter to Iraqi authorities that suggested the United States was about to withdraw its troops. The Pentagon tried to downplay that as a “draft” that should not have been sent. When Trump commented on the issue, agreeing with the Pentagon that the United States was not withdrawing its troops, he nevertheless made clear that, “at some point, we want to get out.”

Nevertheless, Adel Abdul Mahdi, Iraq’s caretaker prime minister, accepted the letter as an official statement — a welcome one, as the Iraqi parliament has voted to force U.S. troops to leave for a second time, having returned to fight Islamic State forces in 2014.

The Post's Mustafa Salim saw anger and grief at a funeral Jan. 4 in Baghdad for Iran's Maj. Gen. Qasem Soleimani and paramilitary leader Abu Mahdi al-Muhandis. (The Washington Post)

As was true for Obama in 2011, Trump may find that declaring victory and going home seems like the best path to reelection.

Andrew Payne (@Andy_J_Payne) is the Hedley Bull Research Fellow in International Relations at the University of Oxford.

Read more TMC analysis of the Middle East crisis: