U.S. President-elect Donald Trump’s flurry of transition pronouncements has made it abundantly clear that the decadeslong era of U.S. passivity in the Western Hemisphere is over. Trump is not simply pronouncing the potential U.S. acquisition of the Panama Canal and Greenland; rather, by his very choice to inveigh on strategic topics in the United States’ own hemisphere and appoint officials focused on the region even before the start of his tenure, he is signaling a profound shift in Washington’s posture toward its backyard.

Trump’s reprioritization of the Western Hemisphere is impossible to ignore. While quickly dismissing a U.S. interest in post-civil war Syria and promising to mediate a swift resolution to the Russia-Ukraine war, Trump has made clear his focus on closing the U.S.-Mexico border to illegal entry; expressed interest in reviving traditional American views of the strategic necessity of both Greenland and the Panama Canal; focused heavily on U.S. security and trade concerns with Mexico and Canada; nominated a secretary and deputy secretary of state with deep Latin America expertise, along with a special envoy for Latin America and 10 regional ambassadorships; and elevated his longtime immigration expert, Stephen Miller, to the role of White House homeland security advisor, further institutionalizing a focus on the southern border and its regional nexus inside the national security process.

This early focus represents a significant departure from several decades of U.S. passivity in the Western Hemisphere, which is itself deeply ahistorical and without roots in traditional American strategic thought. The 1823 Monroe Doctrine famously declared that the hemisphere should be free of European interference, and early U.S. foreign policy was preoccupied with ensuring the country’s interests across this vast region. From Secretary of State William Seward’s purchase of Alaska and proposed buying of Greenland, to the longtime effort to construct a Central American transoceanic canal, to the U.S. conquest of Puerto Rico and Cuba, and to the purchase of the Virgin Islands, U.S. foreign policy long took for granted the requirement to safeguard the region abutting the homeland. With a similar policy of “hemispheric defense” during World War II that was led by Nelson Rockefeller, Washington exerted considerable effort to protect its interests across the hemisphere, such as occupying Greenland, enlisting Brazil and Mexico to join the Allied cause, and assuming control of British naval bases across the Caribbean.

Yet in recent decades, this long tradition of U.S. focus on its neighborhood has been abandoned by presidents of both parties, for different reasons.

First, beginning with President Jimmy Carter’s decision to abandon the Panama Canal in the late 1970s, the United States has too often viewed the region through the prism of perceived historical U.S. policy failures. The construction of the canal, once seen as a strategic masterstroke and engineering marvel, became an example of U.S. imperialism. U.S. involvement in coups in Guatemala, Chile, and elsewhere during the Cold War, along with the stains of gunboat diplomacy during the early 20th century, provided cover for Washington to retreat from active involvement in the region. Rather than addressing issues of historical memory head on, and occasionally even pushing back on false narratives spread by U.S. adversaries, too many of the U.S. foreign-policy elite have accepted the fiction of American perfidy in its hemisphere and chosen to disengage.

Then, as the United States shifted focus to combat Islamist terror and entered into prolonged counterinsurgencies in Iraq and Afghanistan, the Western Hemisphere seemed secure and insignificant by comparison. Washington felt comfortable dismissing the volatile politics of much of the region as essentially par for the course, with little impact on U.S. security if ignored. In a unipolar world and with Washington’s focus largely on the Middle East and South Asia, the hemisphere could be safely dismissed as a backwater.

While Washington was distracted abroad and cowed by self-doubt, U.S. adversaries rushed to fill the void. Since 2000, China’s trade with Latin America has expanded 35-fold, and it is the largest export and import destination for many of the region’s largest economies. More than 20 countries in the hemisphere have joined Beijing’s Belt and Road Initiative, a program designed to gain coercive economic and political leverage over the recipients. China has deep-water port investments with 17 countries and is the telecommunications provider of choice for dozens of countries, both of which pose substantial security concerns.

In addition to gaining significant control in the operation of the Panama Canal, China has continually upgraded its intelligence collection facilities in Cuba, some 90 miles from the U.S. shore; has sent marines to Brazil for joint military exercises; is actively undermining the Antarctic Treaty as it seeks to expand military activities on the southern continent; and is exploring space collaboration across South America. Perhaps most importantly, it is Chinese fentanyl that is pouring unimpeded across the U.S.-Mexico border and killing tens of thousands of Americans.

Despite its setbacks elsewhere, Russia remains interested in Cold War-era gamesmanship with Washington in the hemisphere, backing the Cuban and Venezuelan dictatorships and sending warships to the Caribbean. Iran and its Hezbollah proxies remain active across Latin America. And transnational cartels and gangs pose real threats to U.S. citizens and interests. Rather than a strategic backwater, the hemisphere is the very locus of U.S. security and economic interests in an era of great-power conflict. These interests will become even more vital to U.S. economic security as decoupling measures accelerate and a greater emphasis is placed on promoting secure regional economic blocs.

Trump has begun the process of reorienting Washington’s focus back to the defense of its hemisphere—something that would have been axiomatic for U.S. presidents as diverse as John Quincy Adams, Abraham Lincoln, and Theodore Roosevelt. Rather than apologizing for the United States’ historic leadership in the region, Trump is reasserting U.S. interests at the very time they are under increasing threat from adversaries like China and the global cartels. A policy of hemispheric defense is deeply rooted in U.S. history and strategy, and reviving that tradition could be one of his lasting legacies.