The RGC has been battling drug smuggling gangs along the Afghan and Pakistani border for over a decade, and this has become a major combat operation for them. While Iran and the Taliban did not get along (the Taliban considered Shia Moslems, including Iranians, to be heretics), they both had problems with drugs. Moreover, the Taliban knew that the Iranians could invade western Afghanistan and get away with it. So by 2000, the Taliban were trying to stop the drug smuggling into Iran. Those efforts halted when the Taliban were overthrown in 2001, and Iran moved thousands of its RGC troops to the Afghan border. The RGC were sent partly because they were more difficult to bribe. The drug gangs had plenty of cash, and preferred to bribe their way past the border guards. If that failed, they would shoot their way in. Hundreds of RGC troops are getting killed or wounded each year on the Afghan and Pakistan borders.
The RGC was founded in 1979, as a paramilitary force whose main job was to insure that the regular armed forces remained loyal. Hundreds of thousands of RGC troops also fought in the 1980s war with Iraq, but their main job was always to prevent a rebellion by the armed forces. To that end, a part-time branch of the RGC, the Basj, was assigned to act as lifestyle police all over the country. So, overall, the RGC is not well liked, most people seeing them as spies, busybodies and bullies. There are about 120,000 RGC on active duty, plus several hundred thousand part time Basj.
Iran has nearly three million drug addicts, and these folks are getting supplied from Afghanistan. The drug addiction is seen as a negative thing by just about everyone. The efforts of the RGC to stop the drug smuggling is one effort that these troops are widely respected for. Otherwise, the RGC were seen as a bunch of life-style police and spies, ready to pounce on anyone they thought was not acting properly Islamic.
Concern for the movement of drugs, arms, and probably terrorists, into Iran from Afghanistan and Pakistan, have led the Iranian Revolutionary Guard Corps (RGC) to develop a border security program. Apparently the first step will be to dig a trench along the entire eastern frontier.