No one can say with certainty because it would depend on the circumstances and the decisions of Iran’s leadership at the time.

Most security analysts would say:

  • If Iran acquired a nuclear weapon, the most likely purpose would be deterrence—to discourage attacks by making the potential cost to an adversary much higher. This is how several other nuclear-armed states have historically viewed their arsenals.
  • Actually using a nuclear weapon against another country would carry an extremely high risk of devastating retaliation. For that reason, many analysts believe any Iranian leadership would be very reluctant to cross that threshold.

That said, there are reasons governments remain concerned:

  • Iranian leaders have made hostile statements toward Israel over the years.
  • Iran has supported armed proxy groups in the region.
  • A future crisis or miscalculation could increase the risk of escalation.

So the answer is not simply “yes” or “no.” The mainstream assessment is:

  • Could Iran use a nuclear weapon if it had one? Yes, it is possible.
  • Would it be likely to do so without extraordinary circumstances? Most analysts believe the probability is relatively low because of the near certainty of overwhelming retaliation.

This is one reason why Iran’s nuclear program has been a major international security issue for many years: even a low probability of nuclear use is taken very seriously because the consequences would be catastrophic.