Interviewed on CNN today, retired Gen. John Allen, recently replaced as the US Special Envoy to the war against ISIS, offered an extremely pessimistic assessment of the war, saying that the US needs to address the causes of “symptoms” like ISIS and al-Qaeda, and failing that will be “condemned to fight forever.”

Historically, the US hasn’t been particularly good at even identifying the causes of insurgencies against US-backed governments, let alone making any credible efforts to address those problems. Notably, Gen. Allen didn’t make any real effort to identify the causes he thought the US needs to address either.

Rather, Allen simply insisted that the locals “understand the region better” and that the US should “work closely with them” to resolve the underlying conditions which are fueling growing recruitment to such Islamist factions.

Gen. Allen informed the administration of his intention to resign back in September, citing growing frustration with the administration’s policies in the war, and in particularly in not following through on escalations of the conflict. He’d been warning that he believed the war would last “a generation or more” since last summer.

Allen did mention that he thinks the US should “consider” a no-fly zone in Syria, but conceded that the cost in resources of such a move might be too much to ultimately carry out. The State Department has recently indicated such considerations are off the table because of the cost.

Despite recently resigning and being replaced by Brett McGurk, Gen. Allen said he wouldn’t rule out returning to a government position like Secretary of Defense in the future, saying he’s always willing to “come off the bench if they need the help.”