Iran has emerged as an opponent markedly different from the countries the United States faced in previous military campaigns, Bloomberg reports.

According to the agency, the opening phase of the operation initially unfolded in a familiar pattern for Washington. U.S. cruise missiles began striking targets across Iranian territory, reflecting the traditional American approach of applying overwhelming military force. Yet nearly two weeks into the confrontation, the situation appears far more complicated.

Bloomberg notes that the fighting has proven more intense than many expected. Although Iran’s military budget is smaller than the gross domestic product of the U.S. state of Vermont, the country possesses a large stockpile of missiles and drones. The publication points out that the United States has not previously encountered this particular combination of weapons in past conflicts.

As a result, American forces have been forced to rely heavily on expensive interceptor missiles to counter Iranian attacks. Replenishing those stocks has turned out to be difficult. At the same time, Tehran continues launching strikes against key military facilities across the Middle East.

Bloomberg attributes this capability to Iran’s long-term strategy. For years, Tehran has steadily expanded its missile and drone arsenal while dispersing these systems across different parts of the country.