An Iranian woman rushes past riot police in Tehran in April 2011. (Behrouz Mehri/AFP/Getty Images)

After Iran's disputed 2009 presidential election, protesters and riot police filled Tehran, shutting it down for days in a series of demonstrations some called the "green revolution." This time around, with another presidential vote scheduled for June, the Iranian authorities appear to be taking a more proactive approach.

Hours after Iran's Guardian Council announced that it would not allow former president Ali Akbar Hashemi Rafsanjani to run, The Washington Post's Jason Rezaian reports from Tehran:

Large groups of riot police, the kind that patrolled Tehran’s streets in the days after the contested 2009 reelection of Mahmoud Ahmadinejad, patrolled on motorcycles throughout the capital Tuesday for the first time in more than a year, perhaps in anticipation of the candidate announcement.

Of course, just because Iranian authorities are sending out riot police doesn't necessarily mean they'll need them. But it's a sign of the tension that Rezaian says can be felt there and, perhaps, a show of force.