LONDON – Britain on Wednesday unveiled a campaign to dig itself out from under a mountain of public debt, setting up a global experiment: Can a major nation drastically slash government spending without derailing its economic recovery?

The new Conservative-led coalition headed by Prime Minister David Cameron announced state cuts deeper than the ones made by Margaret Thatcher in the 1980s, outlining a plan to eliminate half a million government jobs, slash welfare benefits and reduce $131 billion worth of other public spending on everything from fighter jets to pensions to the arts by 2015.

The effort puts Britain at the core of the debate over how fast, and how deep, to cut the crushing levels of public debt racked up by the governments from the United States to Europe and now viewed by leading economists as one of the greatest threats to the global economy.

Britain’s pull-the-bandage-off-fast approach now stands in sharp contrast to the thinking in Washington, where senior administration officials are leery of the impact such drastic steps could have on the U.S. recovery, and where further increases in funding are still being considered.

The new coalition is gambling its political future on a bet that Britons will embrace a painful new age of austerity after years of big-spending Labor governments under former Prime Ministers Gordon Brown and Tony Blair.

In the aftermath of the financial crisis — with collapsing tax revenue and soaring stimulus spending — the budget deficit here is now one of the highest in the industrialized world, standing at 11.5 percent of economic output, or slightly higher than in the United States.

Now, budget cuts are set to yank billion out of the British economy, costing jobs that may not be offset by the private sector and potentially stalling the still-fragile economic recovery.

In other European countries, lesser efforts over the past few months to cut public deficits have already yielded increasingly violent strikes, and union leaders in Britain are vowing to turn up the heat here.

In France on Wednesday, angry protestors opposed to government efforts to boost the retirement age clashed with police, blocking roads, smashing storefronts and fencing off fuel depots.

In recent weeks, more limited strikes have temporarily shut down London’s huge Underground transit system, stranding millions of passengers and tourists.

Nevertheless, British officials have decided that a potential loss of market confidence and the weight of the debt on the economy and the British pound are now the greater threat.

“Today is the day when Britain steps back from the brink, when we confront the bills of a decade of debt,” George Osborne, the chancellor of the exchequer, or Britain’s Treasury secretary, declared before Parliament on Wednesday.