ALWAYS keep an eye on the quiet ones. Robert Gates, a Washington veteran who served as George W. Bush’s final defence secretary and stayed on as Barack Obama’s first, has written an incendiary memoir that belies his reputation as an inscrutable, unflappable team player (Team Obama even nicknamed him “Yoda”, after the Jedi master from “Star Wars”). As a rare bipartisan figure in a polarised capital, who served eight presidents in his day, Mr Gates has startled Washington by revealing the passions beneath his poker face. He betrays real loathing for Congress (most members are parochial, incompetent, rude, thin-skinned, self-serving and hypocritical, is his verdict). He talks of congressional hearings turned into kangaroo courts by members “in a permanent state of outrage”. At the same time, Mr Gates, CIA chief during the presidency of the elder George Bush, confesses to the almost-debilitating grief that he came to feel over military casualties.

His book, entitled, simply, “Duty”, shows contempt for many in Mr Obama’s inner circle. Special disdain is reserved for Vice-President Joe Biden, who was “wrong on nearly every major foreign policy and national security issue over the past four decades”. Close Obama aides are dismissed as callow, aggressive, suspicious and leaky. He calls Team Obama more prone to micromanagement of national security than any White House he had seen “since Richard Nixon and Henry Kissinger ruled the roost”. Stung by what he felt were broken promises over defence spending and gays in the military, Mr Gates alleges: “agreements with the Obama White House were good for only as long as they were politically convenient.”

Yet historians may find most interest in Mr Gates’s more-in-sorrow-than-in-anger portrait of Mr Obama, a man 18 years his junior. Republican foreign-policy hawks, such as Senator Lindsey Graham of South Carolina, claim Mr Gates’s book as evidence that Mr Obama has caused havoc from Iraq to Syria by ignoring the military and refusing to lead.

The book’s charge is subtler than that. Mr Gates depicts a president willing to overrule political advisers and take hard decisions, as with his 2009 military surge in Afghanistan. But in Mr Gates’s telling, Mr Obama is oddly reluctant to own those decisions. The Afghan surge is presented as the logical end point of a process that saw Mr Obama win the White House as an opponent of the “bad” war in Iraq, while hailing Afghanistan as a “good” war. Having declared Afghanistan a war of necessity and analysed his options for months, Mr Obama had to come up with a plan for winning. Yet the defence secretary came to doubt whether Mr Obama’s heart was in it. He describes a 2011 meeting overshadowed by rows with the Afghan president, Hamid Karzai, and by unhelpful briefings by General David Petraeus, then the military commander in Afghanistan. Mr Gates recalls thinking: “The president doesn’t trust his commander, can’t stand Karzai, doesn’t believe in his own strategy, and doesn’t consider the war to be his. For him, it’s all about getting out.”

Mr Gates finds some similarities between Mr Bush and Mr Obama, calling both self-contained, aloof and damagingly arrogant with members of Congress or foreign leaders who might be allies. As a self-proclaimed realist, sceptical of the use of military force, Mr Gates is arguably closer in strategic worldview to Mr Obama. Yet he cannot hide his disillusion with a boss who comes across as a detached observer of his own foreign policy. “I thought Obama did the right things on national security,” Mr Gates writes, “but everything came across as politically calculated.” The president earned the respect of Mr Gates, a rare Republican in Team Obama, but never, it seems, his love.