United States assembles some of its most advanced fighter jets, airborne early warning aircraft, aerial refueling tankers, and carrier strike groups in the Middle East, a dramatic encounter from 2013 has resurfaced as a powerful reminder of the staggering technological gap between Washington and Tehran.

As Iran's new academic year began over the weekend, large-scale protests erupted across several universities.

Yet instead of launching military strikes, Washington pursued a diplomatic agreement with Moscow under which Syria declared and dismantled its chemical stockpiles. Critics argued that the decision not to use force weakened American credibility and diluted deterrence.

The figures vary from as few as 3,000 according to the regime in Tehran to over 32,000 reported by President Donald Trump.

Iran's state news agency said students protested at five universities in the capital, Tehran, and one in the city of Mashhad on Sunday.