President Barack Obama's administration is conducting a full policy review on Iran which is expected to include Tehran's role in Afghanistan, while the head of NATO, which leads some 55,000 troops in Afghanistan, said dialogue with Iran was crucial to fighting the insurgency there.
"It is absolutely essential, you cannot stabilize Afghanistan without Iran," said Ahmed Rashid, author of a widely acclaimed book on the Taliban.
Germany, the third largest troop contributor in Afghanistan, has also joined the chorus of diplomatic voices for dialogue with Iran, suggesting recently a "contact group" of nations to kick-start rapprochement.
With the US planning to deploy up 30,000 extra troops to Afghanistan in the next 12 to 18 months, and faced with supply-line challenges over insecure routes from Pakistan, the need for wider regional cooperation is acute and urgent.
"Pakistan has only been partially helpful in fighting al Qaeda and the Taliban ... talking to Iran will put a lot more pressure on Pakistan and neighboring countries to cooperate with NATO and American forces in Afghanistan," Rashid said.
When asked whether any future talks with Tehran might touch on Afghanistan, US State Department spokesman Robert Wood said there needed to be a regional approach to Afghanistan and that included Iran last week.
Alternative routes to Afghanistan for US and NATO supplies have been agreed with Central Asian states to the north, but given its access to major ports on the Caspian Sea and the Persian Gulf, Iran would be an invaluable transit route, though the likelihood of military supplies coming through Iran is a distant prospect.
NATO's top military commander said Monday that the alliance would not oppose individual member nations making deals with Iran to supply their forces in Afghanistan as an alternative to using increasingly risky routes from Pakistan.
"Those would be national decisions. Nations should act in a manner that is consistent with their national interest and with their ability to resupply their forces," Craddock, an American who is NATO's supreme allied commander, told the AP. "I think it is purely up to them."
Securing alternative routes to landlocked Afghanistan has taken on added urgency this year as the United States prepares to double its troop numbers there to 60,000 to battle a resurgent Taliban eight years after the US-led invasion.
It also comes at a time when the main supply corridor through neighboring Pakistan is becoming increasingly dangerous as insurgents attack convoys that supply the foreign troops in Afghanistan.
Some political and military leaders have hinted at the need for closer cooperation with the government in Iran over the war in Afghanistan, where some 70,000 NATO and US troops are currently trying to beat back the resurgent Taliban.
The Islamic Republic has a long history of opposing Taliban rule.
Some experts suggest that nations with good relations with Iran such as France, Germany and Italy may try to set up an alternate supply route to western Afghanistan via Chah Bahar, a port in southeastern Iran.
"NATO is looking at flexible, alternate routing. I think that is healthy," Craddock said, when asked about the possibility of using Iranian territory for supply.
"Options are a good thing, choices are a good thing, flexibility in military operations is essential," he said. "What nations will do is up to them," he said, without elaborating.
Craddock's comments came after US Central Command chief Gen. David Petraeus said last month that America had struck deals with Russia and several Central Asian states close to or bordering Afghanistan to allow supplies to pass through their territory.
US and NATO forces in Afghanistan get up to 75 percent of "non-lethal" supplies such as food, fuel and building materials from shipments that cross Pakistan.