MOST DISASTROUS ERA OF US FOREIGN POLICY

While the initial intent of the Afghanistan invasion was to kill or capture bin Laden, its mission developed gradually, experts said. Over the years, the United States had tried to set up US-style democratic institutions in the country. And it failed.

One part of the US anti-terror strategy was founded on the supposedly "enlightened" idea that "if certain Muslim majority states could be converted into Western-style democracies, then the spawning ground of Islamic fanaticism would be subsumed by a modern Islam and in this way terrorism would be greatly reduced," Robert Lawrence Kuhn, chairman of the Kuhn Foundation told Xinhua.

This strategy was flawed partly because "the Western-style democracy was not suited to the cultural and religious traditions of these countries. Much American blood was spilled and treasure spent in failed missions in Iraq and Afghanistan that caused much suffering," Kuhn said.

He added that one geopolitical theme a historian of the future might characterize the past 20 years is "the end of the American vision of democratizing the world."

Gupta branded the last 20 years as "the ending of an age when America sought to remake the world to its image on the cheap."

"I would submit that the past 20 years, and more broadly the years since the end of the Cold War, will rank among the most disastrous eras in the history of US foreign policy," he said.

Two decades after 9/11, "the world order is no better off and America certainly much poorer off -- reputationally and fiscally," Gupta said.

"The faith that America can naturally go from strength to strength economically, and that every successive generation of Americans can aspire to a better life, has taken a cold shower," Gupta said.

According to the expert, US annual GDP growth registered an average of 3.9 percent over the last six decades of the 20th century.

"During the past two decades, it has struggled to break the 2-percent mark. And this is in spite of the federal government's debt-to-GDP ratio tripling in just 15 years and breaching the problematic 100-percent threshold," he said.

After the Cold War, the United States "could have chosen global leadership by consensus," but it chose to "impose on the world an America-dictated vision of order," Gupta said.

America had the world's sympathy and support after it was attacked, he said. "Yet, the US pressed ahead into Afghanistan with its 'my way or the highway' style and has now departed Afghanistan again in its 'my way or the highway' style."