Trump wants a ‘Department of War.’ Here’s why it’s not called that anymore.

President Donald Trump on Monday reiterated his desire to rename the Department of Defense the War Department, saying the United States had enjoyed an “unbelievable history of victory” in wars fought under its old moniker, which was used until 1947.

“We call it the Department of Defense, but between us, I think we’re going to change the name,” he told reporters during a meeting with South Korean President Lee Jae Myung at the White House.

In a separate White House event on the same day, Trump said he wanted the name change because “we want defense, but we want offense, too.” In June and July, he referred to Defense Secretary Pete Hegseth as his “secretary of war,” saying the name of the department had been changed as a result of political correctness.

But it wasn’t, according to national security scholars and records from the administration of President Harry S. Truman. After World War II ended in 1945, Truman orchestrated a broad reorganization of the old War Department – which became the Defense Department in 1949 – to improve efficiency in national security and cohesion among the Army and Navy, which had been under independent government departments.

“The point was bureaucratic centralization to manage hard power going forward, whose primary goal would be defense, not war (which was) understood as an aggressive act, after the horrors of WWII,” said Krister Knapp, a professor of history at Washington University in St. Louis.

While the Washington Post could not immediately verify how or when a name change could occur, such a move will likely require an act of Congress, because the Defense Department was created through that governing body. The Defense Department could not be immediately reached for comment.

President George Washington created the War Department in 1789. It oversaw the Army, while the Navy and Marine Corps were overseen by a separate Department of the Navy starting in 1798. This structure remained until 1947, when Truman received Congress’s approval to create a National Defense Establishment to oversee the Army, Navy and the newly formed Air Force. In 1949, the National Defense Establishment became today’s Department of Defense.

Truman had announced plans for such a new governing structure as early as April 1946, when he said his policy goal was “unification of all our armed services in a single department.”

“Unification does not mean subordination of any branch of the service,” Truman told a crowd in Chicago, perhaps cognizant of potential resistance among Army generals or Navy admirals viewing his proposal as a threat to their respective service’s traditional autonomy.

“It does not mean a loss of identity. It means just what the word says – unification,” Truman continued. “It means a concentration and cohesion of our best military thought and our best military resources, geared to maximum efficiency. It means using our experience in World War II for the peace of the world.”

Skepticism about the creation of the Defense Department and concerns about losing autonomy to other services erupted in the Navy, in an episode known as the 1949 “Revolt of the Admirals.” Senior Navy officers and reservists conspired unsuccessfully to oust Truman’s secretary of defense, Louis Johnson, whom they viewed as hostile to the Navy.

Truman’s reorganization of the U.S. government’s national security apparatus at this time – which also included the creation of the CIA and the National Security Council – “laid the groundwork” for U.S. strategy during the early Cold War, Knapp said. This general strategy aimed to contain Soviet Russia and other adversaries. “So, deterrence was the new game,” he added.

The Defense Department has watched over four major wars. In the 1950-53 Korean War, it managed a U.S.-led allied force that successfully repelled the invasion of South Korea by a Soviet and Chinese-backed North Korea. From 1965 to 1972, it oversaw the Vietnam War, which led to the deaths of tens of thousands of U.S. service members. In the 1990-91 Gulf War, the department successfully defended Kuwait after it was invaded by Saddam Hussein’s Iraq. In more recent wars in Iraq and Afghanistan, it undertook conflicts that did not have it fighting conventional military foes, with unclear results.

Under the War Department, the United States fought the War of 1812, the Mexican-American War, the Civil War, the wars against Native Americans, the Spanish-American War, World War I and World War II.