On Wednesday, a firefight broke out over Twitter between Senator Tom Cotton and former Secretary of State Hillary Clinton over the letter to Iran authored by Cotton and signed by 46 other GOP senators.

Cotton had responded late Wednesday morning to Secretary of State John Kerry’s statement, “We are not negotiating a legally binding plan” with Iran, by tweeting:

Cotton followed with a tweet asking the obvious question:

Hours later, Clinton, eyeing her chance to deflect coverage away from her email imbroglio, subtweeted at Cotton:

Cotton fired back less than an hour later: