Gen. David H. Petraeus, who came to know the Quds Force commander’s influence when he served in Iraq, once described General Suleimani as “a truly evil figure” in a letter to Robert M. Gates, then the defense secretary. In another letter, he acknowledged the influence General Suleimani had brought to bear in Iraq. “The most sobering surprise of the week was probably the extent of direct Iranian involvement in Iraqi political intrigue,” General Petraeus wrote in an April 2008 letter to Mr. Gates…

“For Qassim Suleimani, the Iran-Iraq war never really ended,” Mr. Crocker said in an interview. “No human being could have come through such a World War I-style conflict and not have been forever affected. His strategic goal was an outright victory over Iraq, and if that was not possible, to create and influence a weak Iraq.”…

“This was the Quds Force’s assessment: ‘We have a golden opportunity. Now we can keep the Americans busy in this country, and as much as we can we should make chaos in this country,’ ” said Mohsen Sazegara, a founding member of the Revolutionary Guards who now lives in exile in the United States.