Reuters reported yesterday afternoon:

Defense Secretary Robert Gates, a holdover from the Republican Bush administration who is expected to step down later this year, has warned repeatedly in the past against further deep cuts in defense spending.

Minutes after Obama announced his austerity plan, the Pentagon renewed those concerns even as Gates endorsed Obama’s commitment to a thorough review before making any cuts.

Obama has pledged that his budget reductions will not compromise national security.

Pentagon Press Secretary Geoff Morrell said Gates “has been clear that further significant defense cuts cannot be accomplished without reducing force structure and military capability.”

The Pentagon said Gates was not informed of Obama’s decision on budget cuts until Tuesday. Morrell said the issue would not affect the timing of Gates’ expected retirement.

Morrell let it be known that Gates wasn’t advised about the proposed spending cuts in advance of the speech. Gates is not alone in voicing concerns:

“The secretary believes that this process must be about managing risk associated with future threats and national security challenges and identifying missions that the country is willing to have the military forgo,” Morrell said.

Obama’s announcement of proposed defense cuts immediately set off alarms in Congress, where the Republican chairman of the House of Representatives Armed Services Committee, Howard McKeon, said he had “grave concerns” about such large spending reductions while the U.S. military was involved in Iraq, Afghanistan and Libya.

As a substantive matter Gates is right. Obama cannot slash defense spending without curtailing our ability to defend national security interests he has identified. Public pushback makes clear that this speech was a political, not policy, statement and a rushed, unthoughtful one at that.

But why is Gates publicly announcing that the commander in chief blew it? It is more than a little disturbing that Gates appears to have junked his respect for the chain of command. Thomas Donnelly of the American Enterprise Institute e-mails me:

Geoff Morrell is a by-the-guidance-book kind of guy, and Secretary Gates was scathing in his criticism of the defense cuts sketched by the Simpson-Bowles panel. And the cuts enumerated by the president would be very painful for the Pentagon, dispiriting to a force struggling to meet the demands of fighting three wars. People in uniform will grumble but follow orders. But perhaps Gates has carried his last water for this president.

Gates’s latest comments certainly defy his own warnings (on Afghanistan strategy) that “it is imperative that all of us taking part in these deliberations — civilians and military alike — provide our best advice to the president candidly but privately.” Gates is no longer doing so, albeit for sound reasons.

Jamie Fly of the Foreign Policy Initiative suggests a different approach. He told me last night, “Secretary Gates fended off previous White House attempts to raid the Pentagon’s coffers but he seems to have lost the latest battle in a big way. If he really believes, as his previous statements indicate, that the type of cuts outlined by the President today will put our national security at risk, he should resign rather than continue to serve in an administration that is increasingly unserious about national security.”

That seems preferable to public insubordination. If he can’t abide by the edicts of this commander in chief (and isn’t consulted in advance on matters that impact his department) maybe it really is time to go.