Five years after Washington launched its hunt for those responsible for the September 11 attacks, the world has not become a safer place, and a new large-scale strike against America at some point appears likely, they say.

Even the killing last month of al-Qaeda's leader in Iraq Abu Musab al-Zarqawi, hailed by the White House as a major blow against the terror network, has not dented its ability to recruit new militants or mount attacks.

In May the influential US magazine Foreign Policy and a Washington-based think-tank questioned 116 leading US experts -- a balanced mix of Republicans and Democrats -- on the progress of the US campaign against terrorism.

Among others, they consulted a former secretary of state, two former directors of the Central Intelligence Agency (CIA) and dozens of the country's top security analysts.

The result? Eighty-four percent believe the United States is losing the "war on terror", 86 percent that the world has become a more dangerous place in the past five years, and 80 percent that a major new attack on their country was likely within the next decade.

"We are losing the 'war on terror' because we are treating the symptoms and not the cause," argued Anne-Marie Slaughter, head of the Woodrow Wilson School of Public and International Affairs at Princeton University.

"Our insistence that Islamic fundamentalist ideology has replaced communist ideology as the chief enemy of our time feeds al-Qaeda's vision of the world," boosting support for the Islamic radical cause, she said.