A U.S. official and Iran's deputy foreign minister shook hands and exchanged greetings on the sidelines of a regional security conference in Moscow over the weekend, foretelling possible further contacts between U.S. and Iranian officials this week on Afghanistan.

FOX News has learned that U.S. diplomat Patrick Moon, who covers South and Central Asia for the State Department, exchanged pleasantries with Mehdi Akhundzadeh during the Shanghai Cooperation Organization summit -- a six-member regional security group that includes Russia, China and Central Asian states. 

The Shanghai meeting on drug trafficking and terrorism included senior British diplomats, the foreign ministers of Afghanistan and Pakistan and U.N. Secretary-General Ban Ki Moon.

Contrary to reports, Moon and Akhundzadeh did not have an actual sit-down, but the encounter in Moscow follows the first talks in 30 years between Iranian and NATO officials, who met to discuss narco-terrorism two weeks ago.

The noteworthy handshake also precedes Tuesday's U.N.-backed conference in The Hague, Netherlands, on Afghanistan. 

That venue could be the stage for Secretary of State Hillary Clinton's first possible encounter with Iranian counterparts, even though State Department officials are not at this point foreshadowing any "substantial" meetings between U.S. and Iranian officials at the conference. 

"It remains to be seen what role the Iranians want to play in Afghanistan. We would like to see them play a positive role, one would hope they are coming with that in mind," a State Department official told FOX News.

Akhundzadeh is expected to represent Iran at The Hague. The conference was proposed by Clinton, and representatives of 90 nations are expected to attend. 

Speaking to reporters at The Hague on Monday, special representative for the region Ambassador Richard Holbrooke said it was "logical" that Iran, one of Afghanistan's neighbors, should attend the meeting. 

Iran is deeply concerned by the Afghan opium trade, most of which passes through its territory.

Iran and the U.S. also share a common enemy in the Taliban. A group of Iranian diplomats were murdered by the Taliban in 1998 and Iran was a long time supporter of the Northern Alliance resistance in Afghanistan.

Finding common ground with Iran on Afghanistan is a priority for the Obama administration, with some U.S. officials suggesting it is the administration's strategic hope that The Hague meeting could break the ice for broader talks on Iran's accelerating nuclear capability.