With Iran, Trump is speaking bigly and carrying a weakened stick

Then came Donald Trump’s brashness, technological advances and, well, bad planning.

Now we are in an era of speaking loudly while carrying a big, but increasingly less relevant, stick.

The reason has less to do with the strength of the American military than with the changing nature of warfare. Cheap drones have lowered the barrier to entry for weaker nations to field precise and deadly weapons. Cyberattacks, proxy forces, and economic disruption have given adversaries new ways to impose costs without matching America’s conventional military power. A country no longer needs to rival the United States on the battlefield to punish it.

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The evidence is mounting. Russia has discovered that overwhelming firepower alone cannot force Ukraine into submission. The Iran-backed Houthis in Yemen, despite being vastly outmatched militarily, have repeatedly disrupted one of the world’s busiest shipping lanes in the Red Sea. And now Iran itself has demonstrated that even a country facing the world’s most powerful military can continue imposing meaningful economic and geopolitical costs without winning on the battlefield.

If the Iran war has taught Americans — and military powers around the world — anything, it is that simply possessing an overwhelming military advantage has its limits. Military superiority is no longer the end-all, be-all.

In a way, the Iran conflict has become the coda to Roosevelt’s mantra. No modern president has spoken as boldly or as publicly as Trump in threatening military force. Yet the usefulness of America’s might has increasingly been discounted by the Iranians, and Trump’s decision to not just threaten Iran but to show his hand has increasingly lessened the effectiveness of those threats.

The high point came on April 7, when Trump declared that unless Iran came to the negotiating table, “a whole civilization will die tonight, never to be brought back again.”

Within hours, however, Trump backed away from that threat even though no new negotiations had been announced.

Over the following months, Trump repeatedly escalated his rhetoric. He warned of a massive attack on Iran. He suggested plans were in place to seize the strategically important Iranian-controlled Kharg Island, through which most of Iran’s oil exports pass. More recently, he declared American forces were “locked and loaded” and threatened “military terror” at levels not seen since World War II.

In none of those cases did Iran appear to be intimidated into making a lasting peace. At best, Trump secured a short cease-fire that collapsed within weeks.

To be sure, the power of the American military and intelligence remains unrivaled. It is precise, quick, and deadly. It can damage nuclear facilities buried deep inside mountains. It can impose naval blockades across vast stretches of ocean. It can assassinate or capture well-protected leaders in hiding.

Yet much of the Iranian leadership has essentially responded with a shrug. They have recognized how much leverage the Strait of Hormuz gives them economically and how much instability they can create without matching America’s military might. Although Iran has suffered major losses to its navy, it has still managed to send energy prices higher, adding to the political pressure on Trump less than 100 days before the midterm elections.

Decades ago, even when American policy in Iraq and Afghanistan proved deeply flawed, presidents could still temporarily stabilize the situation by sending a surge of tens of thousands of additional troops. That was an ace the United States once held. Now, a war-weary public questions putting troops on the ground and in harm’s way.

Today, it should be obvious that Trump cannot simply bomb his way out of the Iran conflict to force concessions. It has no more worked than Russia has been able to bomb Ukraine into submission. Military force remains enormously powerful, but increasingly it is only one tool among many — and often not the decisive one.

All of this suggests that one of the defining questions of the 2028 presidential campaign may be how America’s next leader views military power and how best to use it. The next president will, once again, inherit the world’s strongest military. The harder question is how to make that military matter in an era when America’s adversaries increasingly refuse to fight on America’s terms.

Roosevelt assumed that America could rely on the size of its stick. Ronald Reagan argued for peace through strength. Both ideas still have merit where the premise was to deter war. But the lesson of Ukraine, the Red Sea, and Iran is that strength by itself is no longer enough to win a war. Peace through strength now also requires strategy, restraint, and adaptability.

The challenge for the next president will not be building a bigger stick. It will be knowing when that stick still matters and when something else is required to achieve objectives.

James Pindell is a Globe political reporter who reports and analyzes American politics, especially in New England.