The US Army has concluded that Iran was the only victor of the eight-year US campaign to remove Iraqi president Saddam Hussein and replace him with a democratic regime.

That’s one of the findings of a massive historical study released Jan. 17, the first major military review of the Iraq war’s lessons. Commissioned in 2013 by General Ray Odierno, then the Army’s top commander, it was conducted by half a dozen field grade officers at the US Army War College.

The report consists of two volumes, one on the initial 2003 invasion and another covering the 2007 pivot to counter-insurgency until the majority of US troops were withdrawn in 2011. The final assessment is sobering reading:

At the time of this project’s completion in 2018, an emboldened and expansionist Iran appears to be the only victor. Iraq, the traditional regional counterbalance for Iran, is at best emasculated, and at worst has key elements of its government acting as proxies for Iranian interests. With Iraq no longer a threat, Iran’s destabilizing influence has quickly spread to Yemen, Bahrain, and Syria, as well as other locations. As the conflict expanded beyond its original boundaries, the colonial creation that was the Iraqi-Syrian border was effectively erased. Bashar al-Assad, having misjudged his ability to control the Salafist foreign fighters that he gave safe haven for the better part of a decade, found himself threatened by the very forces that he had exploited to avert an American invasion―an invasion that in actuality was never forthcoming. Syria was plunged into a vicious civil war that devolved into a brutality only seen in the worst conflicts of the 20th century, resulting in a death toll that has topped half of a million, repeated use of chemical weapons, and the worst refugee crisis since World War II. Kurdistan evolved from a proto-state into a de-facto nation, a development that has created deep tensions with Turkey. The danger of a Sunni-Shi’a regional conflict, with potentially globally destabilizing effects, is now greater than at any time since the original schism.

A key misstep identified by the study was failing to apply in Iraq the lessons the US military learned during the Vietnam war. Its authors believe that the first years of the Iraq war were spent re-learning how to fight insurgents. Following Vietnam, the US military treated that war as an aberration, but these officers argue that even future conflicts with rivals like Russia or China are likely to take the form of irregular warfare.

However, the strategic and operational lessons from the Iraq war clearly haven’t sunk in today. The study’s warnings about the dangers of operating in collapsed states, the difficulties of working with local partners and the foolishness of relying on technology to offset small troop deployments seem dire in light of the strategic vacuum still faced by American forces in Syria, Iraq and Afghanistan.

The authors counsel against assuming that war will be short or imposing artificial troop constraints on missions. President Donald Trump is going against that advice with his call to leave Syria immediately. His immediate predecessors, Barack Obama and George W. Bush, similarly tried to keep US commitments minimal, due to political and financial constraints and a lack of clear strategy in the region.

Repeating the mistakes made in Iraq would be costly. That war cost the US more than $2 trillion. Almost 4,500 American service members died, with an additional 32,000 wounded in action. Credible estimates of Iraqi civilian casualties during the war reach as high as 500,000.