For months, university students Ash Bhat and Rohan Phadte had been tracking about 1,500 political propaganda accounts on Twitter that appeared to have been generated by computers when they noticed something odd. In the hours after the February school shooting in Parkland, Florida, the bots, short for robots, shifted into high gear, jumping into the debate about gun control. The hashtag #guncontrol gained traction among the bot network. In fact, all of the top hashtags among the bots were about the Parkland shooting, Bhat and Phadte noticed. Explainer: What Is a Twitter Bot? Twitter under fire Since the 2016 U.S. presidential election, technology companies have come under fire for how their services were used by foreign-backed operations to sow discord among Americans before and after the election. Twitter, in particular,…