Looking back on the Vietnam War, which ended thirty-seven years ago today, former secretary of defense Robert McNamara remarked, “There’s a wonderful phrase: the fog of war.” He explained: “War is so complex it’s beyond the ability of the human mind to comprehend all the variables. Our judgment, our understanding, are not adequate. And we kill people unnecessarily.”

If the twenty-first century is any guide, McNamara’s attempt to solve the riddle of Vietnam was distinctly, and tragically, American. With enemy body counts as his compass, McNamara directed an escalation of U.S. troop levels, airpower and aid after the 1964 Gulf of Tonkin incident. As the North Vietnamese fought on, defying American assumptions, McNamara championed requests for more soldiers, bombs and dollars until resigning in late 1967.

Thirty-seven years since the fall of Saigon, the fog has not lifted, and McNamara’s ghost haunts the recent landscape of U.S. foreign policy. Today, Afghanistan’s fate remains as uncertain as before President Obama upped U.S. troop levels to six figures. Impatience with sanctions, aid and diplomacy give way to calls for military action as the United States debates entering a civil war in Syria and attacking Iran.

For the most powerful nation in the world, wars have not become more difficult to start nor easier to navigate. Yet the American response to every threat and every crisis remains, overwhelmingly, to do "something" and, when that fails, to double down. The problem is not America’s inability to make war simple—rather, pressures to act blind policy makers to the potential costs of action and the limits of U.S. power. Put simply, America is adrift in the fog of more.

In the fog of more, America imagines its enemies everywhere and fears that inaction will trigger unfathomable losses. A half century ago, U.S. policy makers viewed every communist country as an extension of the Soviet Union and China. They feared that a communist government in Vietnam would ignite communist takeovers across the entirety of Southeast Asia—a nightmare that never materialized.

Today, Americans see Iran lurking in every shadow: dictating political outcomes in Iraq, arming our enemies in Afghanistan, propping up the Assad regime in Syria and shaking hands with communists in Cuba. In February, the head of NYPD intelligence warned in the Wall Street Journal, “As the West's conflict with Iran over its nuclear program continues to heat up, New York City—especially with its large Jewish population—becomes an increasingly attractive target.”

In the fog of more, America can’t see its own hand in front of its face. Domestic priorities are relegated to the bottom of the pile because international threats monopolize time and attention. The Vietnam War sidelined Lyndon Johnson’s Great Society reforms, halving the budget of the antipoverty Office of Economic Opportunity in 1966 and leading to $6 billion in nondefense cuts in 1968. Today, U.S. soldiers hunt Taliban in the mountains of Afghanistan while America’s greatest challenges—debt, employment, education and infrastructure—fester on their doorsteps at home.

It’s tempting to grasp for a grand strategy, a singular vision that can pierce the fog. What we really need is to change how we discuss national security. In the American lexicon, being “tough” on national security too often means not hesitating to go to war. Withdrawal signals weakness, while a surge signals strength. Strategic inaction is branded as isolationism and dismissed as appeasement.

To rebalance U.S. foreign policy, new attitudes are needed. Instead of hawkishness, toughness must mean resiliency: the ability to take a blow, take a breath and react accordingly. Strength must mean confidence—in our unrivaled military capabilities, the durability of our democracy, and our willingness to suffer any hardship and pay any price to defend vital U.S. interests. Of course, the terms “vital” and “core” should be used sparingly to describe interests, instead of being the salt and pepper of our national-security conversations.

A new vocabulary can give us politicians who talk less about using U.S. might and more about shepherding strength. We need leaders who aren’t afraid to acknowledge that the United States is safer today than it was during the Cold War—leaders like former chairman of the Joint Chiefs of Staff Admiral Michael Mullen, who has said repeatedly that the greatest threat to U.S. national security is the national debt.

Yet judging by this election season, the fog is here to stay. Mitt Romney has claimed that “Iran's leaders and ambitions represent the greatest threat to the world since the fall of the Soviet Union and before that Nazi Germany.” Providing interventionists of all stripes with ammunition, President Obama issued a directive last year that states: “the prevention of mass atrocities is a core national security interest of the United States.”

And so, tragically, another one of McNamara’s laments rings true: “It isn’t that we aren't rational. . . . But reason has limits.”

Jonathan E. Hillman is a research associate at the Council on Foreign Relations.