"...I was frustrated that it was harder to build support for a diplomatic agreement with Iran than it was to take our country to war in Iraq."

This reminds me of a quote about President Obama from the 'Times profile of Rhodes in 2016: “𝘏𝘦 𝘪𝘴 𝘢 𝘣𝘳𝘪𝘭𝘭𝘪𝘢𝘯𝘵 𝘨𝘶𝘺, 𝘣𝘶𝘵 𝘩𝘦 𝘩𝘢𝘴 𝘢 𝘳𝘦𝘢𝘭 𝘱𝘳𝘰𝘣𝘭𝘦𝘮 𝘸𝘪𝘵𝘩 𝘸𝘩𝘢𝘵 𝘐 𝘤𝘢𝘭𝘭 𝘵𝘩𝘦 𝘢𝘴𝘴𝘪𝘨𝘯𝘮𝘦𝘯𝘵 𝘰𝘧 𝘣𝘢𝘥 𝘧𝘢𝘪𝘵𝘩,” 𝘰𝘯𝘦 𝘧𝘰𝘳𝘮𝘦𝘳 𝘴𝘦𝘯𝘪𝘰𝘳 𝘰𝘧𝘧𝘪𝘤𝘪𝘢𝘭 𝘵𝘰𝘭𝘥 𝘮𝘦 𝘰𝘧 𝘵𝘩𝘦 𝘱𝘳𝘦𝘴𝘪𝘥𝘦𝘯𝘵.

Rhodes thinks that supporting the Iraq was was easier than the Iran deal only through some moral or intellectual failing. The more obvious reason is that normal people saw 𝘴𝘰𝘮𝘦 chance of success with Iraq but 𝘯𝘰 chance with Iran.