Melvyn Leffler, one of the most accomplished U.S. diplomatic historians, tackles these questions in this important book, “Confronting Saddam Hussein: George W. Bush and the Invasion of Iraq,” which relies on British and American archival sources and numerous interviews with key U.S. officials. He concludes that both the ill-advised decision to invade Iraq and the disconcerting lack of planning for the ensuing occupation resulted from a mix of fear, power and hubris.

The terrorist attacks of Sept. 11, 2001, represented a crucial game changer. President Bush and the other members of his administration dreaded another deadly strike. They operated under a heavy sense of guilt for not having prevented the strikes on the Pentagon in Washington and the World Trade Center in New York. And they believed that America’s way of life was under threat.

Leffler, an emeritus professor of American history at the University of Virginia, assesses the Bush administration through the lens of his deep expertise on national security. He maintains that “the Global War on Terror” aimed not only to track down terrorists worldwide but also to protect American democracy and prevent the nation’s transformation into an authoritarian garrison state. Many experts and commentators argued, at the time and afterward, that Bush sought to export democracy overseas to the Middle East and elsewhere. Leffler, by contrast, contends that Bush and his advisers “were not so much yearning to promote democracy abroad as they were seeking to preserve it at home.” But they were imbued with a “sense of exceptional goodness and greatness” and believed in the superiority of “America’s system of democratic capitalism.” This hubris encouraged a strategy that favored deploying America’s overwhelming power to protect the country and its way of life. The terrorist attacks fed this arrogance and blinded the administration to the moral and strategic issues it confronted.

The book discusses in forensic detail the process that led to the decision to topple Saddam Hussein, occupy Iraq and assume direct responsibility for the post-Hussein transition. Challenging another long-standing belief, Leffler repeatedly argues that it was Bush who called the shots. It was Bush who decided to focus initially on Afghanistan, rejecting pressure from Defense Secretary Donald Rumsfeld and his deputy, Paul Wolfowitz, to also go after Iraq.

During the 18 months between 9/11 and the invasion of Iraq, multiple options were considered, and, according to Leffler, the choice of war was never certain or unquestioned. The shared assumption — within the administration as well as among allies and arms-control experts — was that Iraq still had secret weapons-of-mass-destruction (WMD) programs. The new global landscape made the possibility of a WMD-armed Iraq all the more ominous. While there was no proof of any link between the Iraqi regime and al-Qaeda, the possibility that the latter could get hold of WMD justified acting. “No threat worried Bush and his advisers more than the prospect of terrorists getting their hands on weapons of mass destruction,” Leffler writes.

Intelligence was inconclusive and some of it, it was later realized, simply fabricated. But no risks could be taken. With Bush and British Prime Minister Tony Blair working hand in hand — their special relationship matching the one between their countries — the president opted for an aggressive strategy of “coercive diplomacy.” The threat of military action, it was believed, would compel Hussein to finally abide by U.N. resolutions, readmit international inspectors to the country and ultimately disarm. Regime change in Iraq could thus come either by a drastic alteration of Hussein’s attitude or by his forced removal from power.

While coherent in theory, the coercive diplomacy approach generated a policy that was often rigid as well as inconsistent. There was a tension between the threat of imminent action and the need to allow time for a complex WMD inspection after the effort was restarted in the fall of 2002. Working through the United Nations — as Blair and Secretary of State Colin Powell frequently urged — was necessary to gain international legitimacy and support. But it slowed the process and annoyed the many radical unilateralists within the administration, including Vice President Dick Cheney. To compound matters, Bush might have called the shots, but he was unable to impose discipline on a dysfunctional administration marred by divisions, feuding and jealousies, Leffler observes. His study confirms the conflicts that were acutely visible in real time, particularly the clash between the hawkish Pentagon and the much more cautious State Department.

More time would have been needed to discover that there were no secret WMD programs in Iraq. Flawed intelligence, limited interest in nation-building in Iraq, a lack of diplomatic support even from long-standing U.S. allies such as Germany, broad international opposition to the war: All of this, Leffler contends, should have induced greater caution. On the contrary, it seems to have reinforced the self-righteousness that led to war: the “sense of victimhood and ideological purity,” in Leffler’s words, that informed Bush’s Iraq policy.

Aside from asserting these conclusions, however, Leffler doesn’t delve much into this ideological theme. In his laudable effort to bring some complexity to an often-banalized story — in doing the historian’s work, in other words — Leffler tends to neglect the bombastic and exceptionalist nationalism that shaped Bush’s national security rhetoric, particularly after the 9/11 attacks. He offers only some cursory remarks on the essence of such discourse within the administration, in particular the stunningly radical 2002 national security strategy statement, in which the words “freedom” and “liberty” appeared 60 times in little more than 30 pages. It was that language, along with the many excesses of the war on terror, from rendition to Guantánamo, that shocked and horrified world opinion, which had largely sympathized with the United States in the immediate aftermath of 9/11.

Leffler doesn’t discuss the broad, international opposition to the war in Iraq, symbolized by the global wave of antiwar demonstrations in the weeks preceding the invasion. Even more surprising, he doesn’t fully examine the intense diplomatic skirmishes at the United Nations and the major diplomatic defeat Washington suffered when it became clear that a second resolution would have never been approved. Inexplicably, the key role that France played — which is recounted in the other important archive-based work on the war, “A History of the Iraq Crisis: France, the United States, and Iraq, 1991-2003” by French historian Frédéric Bozo — is also overlooked, aside from a weird (and mostly unfounded) jab in presenting France as one of Hussein’s “friends at the United Nations.”

These limits notwithstanding, Leffler’s history of the invasion of Iraq is an important and carefully crafted book, one that will hopefully open a serious scholarly conversation about one of the defining international events of the 21st century.

Mario Del Pero is a professor of international history at Sciences Po in Paris, where he teaches modern global history and the history of U.S. foreign relations.

Confronting Saddam Hussein

George W. Bush and the Invasion of Iraq