The United States has launched a virtual embassy to connect with the Iranian people online.
It went online on Tuesday in English and Farsi, but the US says it is not intended to replace an official diplomatic mission to Iran.
The BBC says Iranians will still need to US embassies in a third country to apply for visas.
The US embassy was closed when militants stormed the premises and seized 52 American hostages in 1979. That sparked a crisis which endured for 444 days.
Announcing the opening of the virtual embassy, the US stressed that dialogue between Americans and Iranians remained essential.
"Because the United States and Iran do not have diplomatic relations, we have missed some important opportunities for dialogue with you, the citizens of Iran," Secretary of State Hillary Clinton said in a video message uploaded to the site.