What will America’s future be like? It can be expected that the United States will continue along the path it has followed in the past. For the foreseeable decades of the 21st century, America will still lead the world. No matter how loudly President Trump calls for retreat, putting America first and refusing to shoulder international responsibilities, the reality is this: among the world’s some 200 countries, like a flock of sheep moving forward, there must always be a lead sheep. Who should lead? Naturally, it will be the biggest, most capable one that everyone trusts. Even if it tries to step back, the others will push it forward—otherwise the flock falls into disorder and cannot move ahead.

Major European powers such as Germany, France, and Britain have sternly criticized Trump, insisting that America must not retreat. Japan has traditionally followed the United States closely. Russia is unwilling to accept this reality, but it has long since lost the strength to compete. Before the 1980s, the Soviet Union still hoped to rival the United States. After the 1990s, it knew it no longer could: with a GDP of about two trillion dollars, how could it compete with America’s nineteen trillion? In recent years, China, under Xi Jinping, has been ambitious, seeking to confront the United States and build an alternative order. Yet few respond, few trust him, and many fear the Communist system he represents. Given the overall trend, it is difficult for the United States to truly retreat.

From its founding, America’s tradition has been to look inward rather than outward. The Puritans wanted only to build their own free homeland in the New World and had little desire to expand abroad. European affairs should be handled by Europeans; the East was too distant and not worth intervening in. By 1890, the U.S. economy was already the world’s largest, yet America did not want to take the lead. During the Spanish–American War, when Spain was defeated in the Philippines, 43 percent of the U.S. Congress opposed occupying the Philippines, unwilling to extend American involvement beyond the Americas.

In World War I, the United States remained neutral at first—let Europe fight its own war. Only when Germany encroached upon American interests did the U.S. have no choice but to enter the war. After World War I ended, America quickly retreated again. President Wilson wanted the United States to join the League of Nations, but Congress rejected it, choosing once more to focus inward rather than lead internationally. Had America stepped forward to lead the world then, World War II might never have occurred.

In World War II, the United States again began in neutrality—letting Europe fight, letting Japan fight—until Japan struck first with the attack on Pearl Harbor. Only then was America forced to retaliate and enter the war. After World War II, the U.S. once again pulled back, occupying no foreign territory. The Philippines was granted independence, and America largely let go. Still, in order to maintain peace, U.S. troops were stationed in places like Germany and Japan as a stabilizing force.

In 2001, New York suffered an unprecedented terrorist attack. Two hundred-story towers collapsed in an instant, and nearly 3,000 people were killed. The American homeland was attacked, forcing the nation to strike back—fighting wars in Afghanistan and Iraq. The Iraq War was launched on the basis of faulty intelligence. After ten years of war, America was exhausted and war-weary. When President Obama took office, he ended the war and withdrew from Iraq. When Trump came to power, he became even more reluctant to intervene.

Yet global turmoil makes non-intervention impossible. The civil war in Syria created waves of millions of refugees that Europe could not contain, destabilizing societies across the continent. When the world’s policeman stands aside, it cannot escape responsibility or blame.