But Pentagon leaders acknowledged afterwards the changes carry additional risk.
Defence Secretary Leon Panetta and a row of top military brass lined the stage behind the President, underscoring support for cuts that they said they know will be criticised as too drastic.
“Our military will be leaner, but the world must know the United States is going to maintain our military superiority,” Mr Obama said. The strategy is designed to contend with hundreds of billions of dollars in budget cuts and refocus the United States’ national security priorities after a decade dominated by the wars in Afghanistan and Iraq.
Devised through a comprehensive review by civilian and military leaders, it centred on the military the country needs after the “long wars of the last decade are over”, Obama said.
Panetta said smaller military budgets will mean some trade-offs and that the US will take on “some level of additional but acceptable risk”.
But he said in a changing world, the Pentagon would have to make a strategy shift anyway. He said the money crisis merely forced the government to face the shift that is taking place now. The president announced the military will be reshaped over time with an emphasis on countering terrorism, maintaining a nuclear deterrent, protecting the US homeland, and “deterring and defeating aggression by any potential adversary”.
“As we end today’s wars and reshape our armed forces, we will ensure that our military is agile, flexible and ready for the full range of contingencies,” he wrote in a preamble to the new strategy, which is titled, Sustaining US Global Leadership: Priorities for 21st Century Defence.
The strategy hints at a reduced US military presence in Europe and says Asia will be a bigger priority. It also emphasises improving US capabilities in the areas of cyberwarfare and missile defence. China is a particular worry because of its economic dynamism and rapid defence buildup.
A more immediate concern is Iran, not only for its threats to disrupt the flow of international oil but also for its nuclear ambitions. Obama’s decision to announce the strategy himself emphasises the political dimension of Washington’s debate over defence savings. The administration says smaller Pentagon budgets are a must but will not sap the strength of a military in transition, even as it gets smaller.
In a presidential election year, the strategy gives Obama a rhetorical tool to defend his Pentagon budget-cutting choices.
Republican contenders for the White House already have criticised Obama on a wide range of national security issues, including missile defence, Iran and planned reductions in ground forces.
The new strategy moves the US further from its long-standing goal of being able to successfully fight two major regional wars - like the 1991 Gulf War to evict Iraqi forces from Kuwait or a prospective ground war in Korea – at the same time.
The document released yesterday made clear that while some current missions of the military will be curtailed, none will be scrapped entirely.
The administration and Congress already are trimming defence spending to reflect the closeout of the Iraq war and the drawdown in Afghanistan.
The massive 662 billion dollars (£427 million) defence budget planned for next year is 27 billion dollars (£14 billion) less than Obama wanted and 43 billion dollars (£28 billion) less than Congress gave the Pentagon this year.