March 11 (UPI) — Donald Trump has called for Iran’s “unconditional surrender” in the war. He has demanded that he be allowed to choose the next leader. And Trump has told Iran’s military and security forces to “lay down their arms,” or be killed.

The decisive force is the missile and bombing campaign conducted jointly with Israel meant to compel the Iranian leadership to capitulate. This is known as “strategic bombing.” And only once in history has strategic bombing forced surrender.

The history of strategic bombing dates to World War I. German Gotha bombers and Zeppelins attacked London, causing panic, marking the first major use of strategic bombing.

In the 1920s, Italian strategist Giulio Douhet described the theory of using air power to deliver victory from the skies, obviating the need for large land armies and navies. Douhet saw that the use of poison gas, the first weapon of mass destruction, would be so deadly as to produce surrender.

“In 1921, Brig. Gen. Billy Mitchell of the U.S. Army Air Service demonstrated the power of air attack by sinking the German battleship Ostfriesland, demonstrating the vulnerability of warships to air power. Of course, the U.S. Navy protested. But all the major powers began to investigate the utility of strategic bombing.

During World War II, Nazi Germany and fascist Japan believed the best use of air power was tactical — to destroy the enemy’s military.

For Germany, air power became vital to the success of the Blitzkrieg, with Stuka bombers providing close air support to armored and ground forces.

Japan executed the attack on Pearl Harbor that sank much of the U.S. battleship force, but missed the aircraft carriers and submarines that ultimately sent the Japanese Navy to the bottom.

“After France fell in June 1940, Hitler shifted the Luftwaffe from attacking RAF airfields to bombing British cities — the Blitz — after Churchill ordered a retaliatory strike on Berlin.”

That spared the RAF, allowing it to win the decisive Battle of Britain. And other than launching a few balloon-carried bombs against the U.S. West Coast that did no damage, Japan had no strategic bombing campaign.

The U.S. Army Air Force became the chief proponent for strategic and daylight bombing, using throughout the war Britain as its base, as well as using islands in the Pacific that had been captured by the allies.

The question was which strategic targets would most damage the enemy? Britain’s air chief marshal, Sir Arthur “Bomber” Harris, believed that bombing the civilian infrastructure would provide the greatest leverage. Many Army Air Force generals concurred.

Beyond striking military targets in occupied France and Europe, B-17s, B-24s and British Lancasters dropped millions of bombs on Germany. “Raids on cities such as Dresden, Berlin, and Hamburg killed tens of thousands, with firestorms consuming entire districts.”

The same was true in Japan. As Marines occupied more islands, B-29 strikes firebombed Tokyo, Nagoya and Osaka, killing hundreds of thousands of Japanese a night.

In Germany at the height of the bombing campaign in fall 1944, German industry produced more planes, ships and equipment than at any time in the war, revealing the flaws in strategic bombing. Japan, however, presented a more serious problem. Despite the deadly bombing attacks, Japan refused to surrender.

President Harry Truman was confronted with the prospect of invading Japan, risking possibly 1 million U.S. and allied casualties. Given Japan’s suicidal resistance, millions of Japanese deaths were anticipated. Truman had another choice. He authorized dropping the first atomic bomb.

Hiroshima was devastated, killing an estimated 70,000 people instantly.” Still, Japan refused to surrender. A second bomb destroyed Nagasaki. After the emperor broke the tie in the war council, Japan surrendered unconditionally. Why?

Japan’s leaders could tolerate 1,000-plane raids killing hundreds of thousands people in its cities. But one plane, one bomb, one city gone was inconceivable. That was pure shock and awe. And only nuclear weapons could produce that.

The lesson is clear. Strategic bombing with conventional weapons has never forced unconditional surrender on its own. It did not work in Vietnam, Iraq or Afghanistan. It will not work in Iran. Ground forces are needed. And it is far from clear despite concerns that the 82nd Airborne Division may be diverted to the Gulf that the Trump administration will use ground forces.

As the war continues, the United States and Benjamin Netanyahu’s Israel may be running out of targets for air power. Then what? The Trump administration has not answered that question.

Harlan Ullman is senior adviser at Washington’s Atlantic Council, chairman of a private company and principal author of the doctrine of shock and awe. His next book, co-written with Field Marshal The Lord David Richards, former U.K. chief of defense, will be Who Thinks Best Wins: How Decisive Strategic Thinking Will Prevent Global Chaos and is due out in the fall.. The writer can be reached on X @harlankullman.