Why it’s called the Department of “Defense” in the first place — and why Trump wants to change it

President Donald Trump is expected to sign an executive order on Friday renaming the Department of Defense the “Department of War.” The move on its own has no legal power; officially changing the name would require approval by Congress, though the White House is reportedly looking for ways around that. Changing the signage and branding for the government’s largest department, with facilities and bases around the world, would also be extremely expensive. As Reuters notes, the Biden administration’s now-scuttled plan to rename just nine Army bases that honor Confederate leaders was set to cost around $39 million.

Why is it worth it? In an Oval Office event last month, Trump explained that the name Department of Defense “didn’t sound good to me … it used to be called the Department of War. It had a stronger sound, and as you know, we won World War I, we won World War II, we won everything. Now we have a Department of Defense; we’re defenders. I don’t know.” Addressing Defense Secretary Pete Hegseth, who has made “lethality” and “warrior ethos” buzzwords during his tenure at the Pentagon, Trump added, “if you want to change it back to what it was when we used to win wars all the time, that’s okay with me.”

So why does the US have a Department of “Defense”? Trump is correct that prior to World War II there was a Department of War, but it wasn’t quite the same institution. That department oversaw the Army, while there was a separate Department of the Navy.

President Harry Truman and other military leaders felt that this fragmentation had hampered US operations during World War II and even, Truman argued, contributed to the failure to prevent the attack on Pearl Harbor in 1941.

“There were tremendous bureaucratic squabbles between the Army and the Navy and the emerging Air Force over the allocation of financial resources,” Melvyn Leffler, a historian at the University of Virginia, and the author of a book on Truman and the origin of the Cold War. “Truman and his top national security advisers believed that it was essential to integrate and rationalize both national security planning and the preparation of the war plans.”

The National Security Act of 1947 combined the Army, Navy, and the newly independent Air Force into one department under one Cabinet secretary. The department was originally known as the National Military Establishment but changed soon after to the Department of Defense. (NME: not the best acronym.)

Leffler says the choice of “defense” rather than “war” was very deliberate, coming at a time when the US-Soviet Cold War was just getting started and the advent of nuclear weapons had dramatically raised the stakes of conflict between superpowers.

“An overarching preoccupation of President Truman and his advisers was to deter future wars, rather than to wage war,” said Leffler. He also noted that the change came at a time when the US government was taking a more expansive view of national security — the CIA and the National Security Council were also created in 1947 — with the aim of deterring wars in addition to preparing to fight them.

Of course, the US has fought more than its share of wars since then, as advocates for the name change point out. “The U.S. became a much more interventionist power after the creation of the Department of Defense subsumed the Department of War (and Navy) in 1947,” former Hegseth aide and intervention critic Dan Caldwell wrote on Twitter. “Renaming DoD the Department of War is just acknowledging the reality of what DoD’s actual role has been the last 80 years.”

At the same time, the US has managed to avoid getting into major and potentially catastrophic wars with peer adversaries, the nightmare scenario for Truman and his aides in 1947, and a very relevant concern today with rising tensions between the US, China, and Russia.

Leffler is concerned that “changing the name from defense to war implies a much greater desire to engage in bellicose policies. That might lead to actual armed conflict.”

It’s also notable that the proposed name change comes as the Pentagon — whatever you want to call it — is prioritizing homeland security over preparing for a potential war with China and also appears to be dramatically expanding the remit of the US military, both in the Western Hemisphere and on the streets of American cities — not places where, officially at least, we are at “war.”