What are Trump’s military options?

Last week, it was reported that US President Donald Trump placed massive attacks on Iran on hold after a meeting with advisers at the White House. Clearly, domestic political pressure on him and on the Republican Party over rising economic costs is fierce. Current polls suggest nearly 70 percent of Americans oppose the war.

Despite assertions, notably by Secretary of Defense Pete Hegseth, that Iran’s military has reached “its lowest point ever”, Iran is still able to conduct massive drone and missile strikes. Some intelligence suggests Iran has reconstituted and increased its capacity to build these weapons.

Meanwhile, the US has moved more aircraft and missile defence units in preparation for what may be a campaign to target staging points for Iranian forces. Two Marine Expeditionary Units (MEUs) and components of the 82nd or 101st Airborne are currently stationed in the region.

Yet, reports that the US and its Gulf allies have exhausted defensive missile magazines, as well as Tomahawk land-attack missiles, may be a powerful constraint.

While Trump appears not to have made a decision yet, he has several options on how to move forward.

The first option is ramping up air and missile strikes. One of the challenges of this strategy is that the list of military targets may have been exhausted. If so, expanding the aerial campaign would mean attacking largely civilian infrastructure, including energy production facilities, electricity and power grids, bridges and roads, and television and phone networks. The likely outcomes are all bad.

Trump would be accused of war crimes. The Iranian public would coalesce in their resentment against the US. Iran’s ability to strike back would not be significantly curbed and it may strike Gulf desalination and energy infrastructure. The result would be a humanitarian catastrophe. No plans exist to deal with this contingency. And of course, oil could soar to $150 or even $200 a barrel, triggering an international economic disaster.

Another option is a ground invasion of some sort. The forces currently deployed in the region are too small to achieve any realistic military objectives. A MEU numbers about 2,500 marines and only 800 of them are infantry, able to conduct very limited ground operations. Airborne units deploy with only a few days worth of bullets, beans and batteries. Resupply is essential for these units.

As retired US Army General Barry McCaffery has pointed out, even 150,000 troops may not be enough to secure control of the Strait of Hormuz along the Iranian coast.

Attacking Kharg Island requires a long and dangerous transit from the western end of the Strait of Hormuz. That would create conditions for a high number of casualties among US troops.

The third option is for Trump to employ a nuclear weapon, at least as a demonstration shot. That would open a catastrophic Pandora’s box of consequences. Trump would be declared a war criminal. Wherever and however the weapon is detonated—an air or surface burst—it would have destructive outcomes.

If exploded exoatmospherically, the nuclear bomb would emit an electromagnetic pulse (EMP) which would destroy virtually all chip-installed systems for hundreds of miles beyond Iran. Few modern militaries, including in the Gulf, are protected from EMP due to costs. A surface burst would form a radioactive cloud that would travel east given the winds and affect populations well beyond Iran.

A major geopolitical consequence would be that such an attack could change the way Russia’s President Vladimir Putin sees the possibility of using nuclear weapons in the war in Ukraine.

Given this list of unpalatable options, the most promising is to claim victory and pursue negotiations. Trump will say he has brought Iran to the negotiating table even though talks between Washington and Tehran have not stopped despite the escalation. The first issue would be reopening the Strait of Hormuz and Bab al-Mandeb. Oil prices would drop. Stock markets would rebound.

Trump would take the credit. And a devastating war and economic crisis would be sensibly avoided. This is his best and only sensible option.

The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial stance.