Past research has found that third party pressure makes the signing of a ceasefire more likely, but also more likely to break down. What explains this variation? I argue that third party pressure is more likely to lead to a durable ceasefire if pressure is applied to persuade the conflict parties to continue to negotiate and produce a detailed ceasefire document, whereas pressure solely aimed at making the conflict parties sign a ceasefire document undermines the durability of the ceasefire. A comparison of four ceasefires concluded in Sudan supports this argument. Third party pressure that led to the Nuba Mountains Ceasefire and the Agreement on Security Arrangements helped move the negotiations on security arrangements forward. By contrast, the N’Djamena Ceasefire Agreement and the Darfur Peace Agreement were imposed on the parties without regard for political and technical aspects of the ceasefire. This explains why violence soon resumed.