Obama also said he believes that the international economic sanctions, some of the "strongest" ever imposed against Tehran, are having an effect on the country.

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Such persons shall be treated as persons covered by section 1 of Proclamation 8693 of July 24, 2011 (Suspension of Entry of Aliens Subject to United Nations Security Council Travel Bans and International Emergency Economic Powers Act Sanctions).

WHITEHOUSE: Executive Order from the President regarding Authorizing the Implementation of Certain Sanctions Set Forth in the Iran Threat Reduction and Syria Human Rights Act of 2012 and Additional Sanctions with respect to Iran | The White House

We and our European partners agree that path will lead to international isolation and progressively stronger political and economic sanctions.

NPR: In Policy Shift, U.S. May Meet with Iranians

The construction of politically-powerful new constituencies in Western nations with a vested financial interest in ensuring that the borrowing nation is not subject to future economic sanctions or other forms of international isolation and penalties.

CENTERFORSECURITYPOLICY: Center For Security Policy

Iran's repeated failure to ease international concerns has led to a gradual tightening of economic and political sanctions.

BBC: Iran's Khamenei rejects US nuclear talks offer

Musharraf said Pakistan, which is under U.S. economic sanctions that were imposed after its nuclear testing in 1998, must face a choice between joining the international community -- thereby gaining the ability to influence decisions on the use of force against Afghanistan -- or being cut off.

CNN: Pakistan's delicate position