When Tony Blair, the British prime minister, resigns in the next few months after 10 years in power, Benn is seen as a potential candidate for either deputy premier or foreign secretary if, as expected, Gordon Brown, the finance minister, replaces Blair.
Addressing the Center for International Cooperation think tank in New York, scene of the September 11 attacks in 2001, Benn contested the words "war on terror" to describe a policy launched by President George Bush after those attacks. He did not specifically mention US policy.
"In the UK, we do not use the phrase 'war on terror' because we can't win by military means alone, and because this isn't us against one organised enemy with a clear identity and coherent set of objectives," he said.
"What these (terrorist) groups want is to force their individual and narrow values on others, without dialogue, without debate, through violence. And by letting them feel part of something bigger, we give them strength."
Benn's speech appeared to reflect a shifting tide in British politics after the strongly pro-American policies of Blair, which antagonised left-wingers in his Labour Party. They hope Brown, if he takes over, will be cooler to Washington.
In implied criticism of Bush's emphasis on armed might and sanctions to deal with Washington's foes, Benn also said "hard power" - military and economic force - needed to be complemented by "soft power" - values and ideas.
Support to ICC
Achieving global peace and prosperity required give and take, Benn said. "This is how we can make the argument with those who would act unilaterally, that there is another way."
Benn reaffirmed Britain's support for the International Criminal Court, which the United States has refused to join to prevent US soldiers or officials ending up in the dock. He also repeated British calls for the US Guantanamo Bay detention centre on Cuba for terrorism suspects to be closed.
Benn was speaking after attending weekend meetings of the World Bank and International Monetary Fund in Washington, where he said the scandal over World Bank President Paul Wolfowitz's promotion of his female companion had damaged the institution.
Benn repeated those concerns on Monday. "Let's be blunt about this, what's happened is very, very damaging to the bank ... and it simply can't continue," he told a questioner.