Meanwhile, Washington has what appears to be fresh evidence that Venezuela supported Colombian guerrillas that the U.S. considers terrorists. Yet the terrorism list does not include Venezuela, a major oil supplier to the United States.
Nearly three decades after its inception, the state sponsors of terrorism list is not just about terrorism. It has become a diplomatic tool to win concessions from U.S. adversaries eager to end the stigma and sanctions that come with the designation. It may also be too blunt a tool to be used against strategically important countries, even if the terrorism link appears clear-cut.
"Of course the list is political," said Bruce Hoffman, a professor of security studies at Georgetown University.
The United States has many blacklists for people, groups and countries it deems unsavory. But the state sponsors of terrorism list has perhaps the highest profile, though only five countries are on it: Cuba, Iran, North Korea, Sudan and Syria.
Those countries designated by the U.S. face restrictions on foreign aid, a ban on defense sales and other sanctions that can hinder their acquiring U.S. technology or doing business with U.S. financial institutions.
The penalties can extend beyond U.S. borders. The United States will use its weight at the United Nations and world financial organizations to try to block assistance to designated countries. The designation could also discourage U.S. allies and multinational corporations from dealing with the designated nations.
By contrast, getting off the list is a sign of a return to the global community.
"This is exactly the purpose: to offer carrots and sticks to engage states and then to use this as a means to persuade them to desist from activities that we think are harmful to America," Hoffman said.
The president may rescind the terror designation by submitting a report to Congress that certifies a country has changed policies and has provided assurances that it will not support future acts of terror.
But terrorism often is not the only factor that determines whether a country will be removed.
Libya got on the list because the U.S. blamed it for terrorist attacks that killed Americans in the 1980s. But it took more than its pledge to stop supporting terrorism and pay compensation to the families of terror victims to get it off the list in 2006; it also had to abandon its weapons of mass destruction programs.
James Lewis, a former State Department official who worked on sanctions in the Clinton administration, said the list gives the United States leverage on non-terrorism issues.
The message is: "Do the right thing and we'll take you off the list," said Lewis, an analyst at the Center for Strategic and International Studies think tank.
That appears to be the case with North Korea. Kim Jong Il's government has not been tied directly to terrorism since its agents planted a bomb on a South Korean commercial jetliner in 1987. But there was little talk of removing the North from the list until it became a key point in international talks aimed at ending North Korea's nuclear weapons program.