After taking office, President Obama embarked on one of the riskiest experiments in American history. He decided to see what the world would look like if the United States pulled back from its role as guarantor of global stability and underwriter of the international order.

Six years later, we know.

The more we withdrew, the more unstable the world became. The more we tried to let others lead, the less we could influence or control events. Today, we are less able to deter war and keep the peace — and far more exposed to terrorism — than when Obama entered office.

These are the conclusions William Inboden of the University of Texas at Austin and I drew in our chapter in “Opportunity for All, Favoritism to None,” Heritage Action for America’s new policy playbook for Congress. We set out to understand the predicament America is in because of the president’s failed experiment and to offer a way out.

Our predicament is indeed dire. Terrorism once again threatens our homeland. As we have retreated from the world, large swaths of territory have sunk into chaos, becoming breeding grounds for terrorists. The administration has made far too many unforced errors: pulling out too quickly from Iraq (and likely Afghanistan); neglecting the Syrian conflict until it could not be ignored; forgoing crucial intelligence by attacking terrorists with drones instead of interrogating them; and releasing detainees from Guantanamo to return to the fight.

The mistakes stem, of course, from the myopic view that there really is no war on terrorism. Not even the French believe that anymore.

Then there is the return of great power rivalries. The biggest embarrassment is the failure of the administration’s infamous “reset” policy toward Russia. It has resulted in Russia’s occupation of Crimea and other parts of Ukraine and a new Russian challenge to the post-Cold War settlement in Europe. Obama may talk nonstop about “outdated Cold War stereotypes,” but the new cold war with Moscow fired up on his watch, not President Bush’s.

Though these are our most obvious problems, there is a much bigger one. Word is getting around that the U.S. may be leaving the superpower business. The main culprit is Obama’s diffidence as a world leader, witnessed most recently by his failure to send someone of higher rank than ambassador to the Charlie Hebdo march in Paris. Our perceived weakness enters everyone’s calculations. Neglected allies start looking for other kinds of protection. Enemies and rivals see opportunities they could not have imagined six years ago.

How do we reverse course? It will take more than words to clean up after Obama’s failed experiment.

For starters, there has to be a fundamental change of mind. We have to abandon the notion that letting events drift is less dangerous than trying to control them. We can’t manage everything that happens in the world, but throwing up our hands as if we were powerless — or worse, engaging only halfheartedly as we are now doing against the Islamic State group — is bound to fail.

Changing course means regaining the initiative in the war on terrorism, first by calling it an actual war and second by developing a more coherent policy toward weak and failed states that will keep them from becoming terrorist safe havens. It also means investing more into America’s armed forces.

We must repair and strengthen our alliances and reinvigorate our international economic policy. Our neglect of trade and other economic policies has allowed China and others to fill a vacuum we left behind. It is detrimental to the U.S. economy and to the larger cause of establishing international norms and standards for business and finance.

Obama’s grand experiment has failed. Doubling down on its mistaken premises won’t produce better results. A new course is needed, one that actually worked quite well for decades: a strong America dedicated to leading the free world.

Originally appeared in the Washington Times.