The problem is compounded by their strategic interests in each other's backyard, including Iran's strong influence in Afghanistan as Tehran strives to become a nuclear power, leaning toward Russia, China and India to create a strategic counterweight to the United States, they said.

Drugs in Afghanistan, the world's biggest producer of opium, is deeply tied to warlords, terrorists and drug mafias within the country.

The drug trade is fuelling Pakistan's booming heroin market and increasing addiction among youths, as well as social ills in Iran, the conference organised by the Woodrow Wilson International Centre for Scholars in Washington was told.

Terrorism is a major problem in the region, with the Afghanistan-Pakistan border a key hideout for the al-Qaeda network, including possibly terror mastermind Osama bin laden.

Aside from being accused by the United States of having a covert nuclear weapons program, Iran has been blamed for backing terror groups in the region.

"Afghanistan, Pakistan and Iran are a troubled triangle and the US strategy now is to involve the US government in the region in a way to reduce the troubled nature," said Larry Goodson from the US Army War College.

But while a long term American commitment can help Afghanistan wean itself from drug dependency and boost reconstruction of the war-wrecked nation, and restore democracy to military-led Pakistan, it might fuel greater anti-American sentiment in the region, he warned.

"The US faces, as it does in Iraq, a real conundrum in that we have to stay in order to achieve strategic interest of stabilising and transforming these troubled regions but our very presence there is going to continue to attract some of the more militant jihadists who want to challenge their conception of the US project for the world," Goodson said.

"Anti-American attitudes are at an all-time high in some areas. We really can't stay and yet we dare not go," he said.

In the first salvo on its global "war on terror," Washington led an invasion of Afghanistan in late 2001 to overthrow the hardline Taliban regime for backing al-Qaeda, which staged the deadly terror attacks on the United States.