By Greg Jaffe, Washington Post

There’s one foreign policy fact that President Obama and Mitt Romney dare not mention this election season. No American general will speak of it. Nor will it displace the usual hot topics at Washington’s myriad foreign policy think tanks.

Measured by most relevant statistics, the United States — and the world — have never been safer.

Obama says terrorist networks remain the greatest threat to the United States. “We have to remain vigilant,” he warned recently. But global terrorism has barely touched most Americans in the decade since Sept. 11, 2001, with 238 U.S. citizens killed in terrorist attacks, mostly in war zones, according to the National Counterterrorism Center’s annual reports. By comparison, the Consumer Product Safety Commission found that 293Americans were crushed during the same stretch by falling furniture or televisions.

Beyond the United States, global statistics point undeniably toward progress in achieving greater peace and stability. There are fewer wars now than at any time in decades. The number of people killed as a result of armed violence worldwide is plunging as well — down to about 526,000 in 2011 from about 740,000 in 2008, according to the United Nations.

The candidates’ rhetoric, however, suggests that the globe is ablaze. “The world is dangerous, destructive, chaotic,” Romney said this summer in a speech to the Veterans of Foreign Wars convention in Nevada. Obama, though less apocalyptic than his Republican challenger, routinely talks about the critical need for “tested and proven” leadership in a “world of new threats and new challenges.”

When it comes to foreign policy, the incentives on the campaign trail run toward ruin: Aspirants to public office praise the troops and preach the possibility of global doom.

That makes sense in the looking-glass world of campaigning. A candidate who talks about the declining threat to Americans can quickly appear foolish, weak or out of touch if there is an attack on the homeland or an unexpected setback abroad. In his speech at the Democratic National Convention, Obama proudly declared that “al-Qaeda is on the path to defeat.” Five days later, on the anniversary of 9/11, an attack on the U.S. diplomatic mission in Benghazi left four Americans dead, including the ambassador to Libya, Chris Stevens.

Stevens’s death at the hands of a possible al-Qaeda affiliate forced the president to temper predictions of the group’s demise. More recently, he has even accused Romney of underestimating the threat posed by the terrorist group. “I’m glad that you recognize that al-Qaeda’s a threat because a few months ago, when you were asked what’s the biggest geopolitical threat facing America, you said Russia — not al-Qaeda,” Obama chided Romney at the last presidential debate.

In recent weeks, Romney has shifted his focus to the Iranian nuclear program. “Iran is the greatest national security threat we face,” he said during the final debate.

The news media, meanwhile, almost never take candidates to task for incorrect predictions of disaster. “The political penalty for being wrong about the threat or underestimating it is much more severe than the penalty for overstating it,” notes Peter Feaver, who was a senior official on the National Security Council under President George W. Bush.

Presidential candidates, eager to prove they have what it takes to be the leader of the free world, talk about threats so they can cast themselves as potential saviors in an increasingly dangerous world. “It does not further anyone’s career to say we are safer,” said Micah Zenko, a fellow at the Council on Foreign Relations who uncovered the fatality statistics about terrorism and falling furniture.

Touting global peace may also be “distinctly un-American,” asserts Steven Pinker, a Harvard psychology professor and the author of “The Better Angels of Our Nature: Why Violence Has Declined.”

Pinker offers this theory: Americans want leaders who embrace the country’s role as the sole superpower and confront all adversaries. “A historical peculiarity of the U.S., compared to Europe, is a ‘culture of honor,’ in which a man has to defend himself against threats and insults,” Pinker said.

If he is correct, perhaps it makes sense for Romney to accuse Obama of conducting an “apology tour” of the Middle East that showed weakness and emboldened Iran, China, Russia and other U.S. rivals. Obama has scoffed at Romney’s characterization of his trip, but the challenger has persisted in trying to portray the president as uncomfortable with America’s military might.

The incentives to play down safety also extend to America’s military and intelligence officials, who must live on high alert, scanning the horizon for potential threats to American power. Because these officials know they will be blamed in the event of an unexpected attack, they are more prone to sound the alarm.

“My job as a war planner was to look for all the bad stuff,” said Janine Davidson, who until recently served as a senior civilian planner in the Pentagon. “Scanning for threats is what we get paid to do.”

Most top Pentagon officials say the statistics showing that the world is safer are irrelevant and don’t reflect the magnitude of the risks. The result is what Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, has dubbed a “security paradox.” The world may seem safer, Dempsey says, but the potential for global catastrophe has grown as the planet has become more interconnected and potential enemies have greater access to more powerful weapons and technology. Individuals with simple laptop computers can launch cyberattacks capable of crippling major corporations. Small countries and terrorist groups, such as Hezbollah, can buy precision-guided bombs that were previously the province of superpowers.

Not everyone buys Dempsey’s paradox. The Europeans, who have slashed their defense budgets over the past two decades, don’t seem especially worried about these threats. Some academic researchers also question Dempsey’s logic.

“Should we really predict that the combined expertise and efforts of the American government, universities [and] corporations will be outsmarted for extended periods of time by some unemployed young men in Bulgaria?” asks Pinker, the Harvard professor.

What’s missing is any serious effort to study whether the decline in state-on-state war, violence and terrorism around the world means that the United States can scale back its spending on defense. Each year the Rand Corp., a government-funded think tank, publishes dozens of reports on potential threats to the United States. Recent papers have focused on the Iranian nuclear challenge, the North Korean missile threat, the security of sea lanes in Asia and the rise of new military powers such as India and Brazil. The think tank has never explored the implications of a statistically safer world.

“Why can Smokey’s fire-danger index go down but the nation’s threat level not?” said Gregory Treverton, the director of Rand’s Center for Global Risk and Security. “It’s a good question.”

There are tangible benefits to overspending on security: The United States is more prepared for a broader array of catastrophes than any other nation on Earth. It’s also possible that the government’s massive investment in defense — which exceeds the combined outlays of the nations with the next 10 largest defense budgets — is responsible for the current era of stability and the decline in deaths. This is the essence of President Ronald Reagan’s promise, reiterated in recent weeks by Romney, of “peace through strength.”

But the heavy investment also carries a cost. U.S. defense spending, adjusted for inflation, is at the highest level since World War II and is unlikely to decline substantially. Potential adversaries, such as China, could view the trillions that the United States is spending as a threat in itself, triggering an arms race — and a less-safe world.

For now, though, no one is rushing to discuss the implications of a world that has grown safer.