The vast, powerful American military - politically untouchable since 9/11 - faces sweeping cuts in the new war on spiralling debt.
It's a battle other Western nations, including Canada, face. In the United States, the scale of Pentagon cuts is huge.
``More of nearly everything is simply not sustainable," said Defence Secretary Robert Gates, the only Bush-era cabinet secretary retained by President Barack Obama.
Still the new threat looms. The United States faces "extreme fiscal duress," Mr. Gates admitted. Among the biggest casualties - a $14-billion runaway effort to build sophisticated new armoured expeditionary vehicles for the U.S. Marines and the problem-plagued vertical takeoff version of the new F-35 warplane.
But the cuts - estimated at $78-billion over five years on top of $100-million in savings Mr. Gates says can be slashed from Pentagon bloat - remain predicated on some risky assumptions. Not least, that Americans can come marching home in huge numbers from Afghanistan by the promised exit date of 2014, allowing both the army and the Marines to cuts tens of thousands from their ranks.
Even after cutting 27,000, the army would have 540,000 soldiers in 2015. The Marines would cut 20,000 to about 180,000.
"The Pentagon cannot presume to exempt itself from the scrutiny and pressure faced by the rest of our government," Mr. Gates said.
But the new Republican majority in the House of Representatives may find itself under fire if military spending is slashed so severely that soldiers start suggesting the government is skimping on what's needed to win the war against Taliban insurgents in Afghanistan, and, more broadly, Islamic extremism.
Despite the proposed cuts, Pentagon spending will still grow to $553-billion - albeit at a smaller rate - next year. And the budget doesn't include the cost of fighting the war in Afghanistan or the drawdown in Iraq.
Battle lines were drawn within hours of Mr. Gates's announcement.
"I'm not happy," said Howard McKeon, a California Republican and the new chairman of the powerful House Armed Services Committee. "This is a dramatic shift for a nation at war and a dangerous signal from the commander-in-chief."
Other critics accused the Obama administration of a clever shell game, slashing a few big-ticket military programs but mostly moving the supposed savings to other programs.
Mr. Gates was digging in against attacks from those who want deeper defence cuts sooner.
He warned against those who would seek "drastic and ill-conceived cuts."