A team of U.S. investigators visited Libya's second city Benghazi on Thursday to examine the site where Ambassador Chris Stevens and three other Americans were killed in an attack last month.

"An American investigative committee visited the site where the U.S. ambassador was killed," a defense ministry official in Benghazi told Agence France Presse, confirming that the team included FBI agents.

Mitt Romney regained momentum in the first debate by aggressively standing up to Barack Obama, analysts said, but it remains to be seen how much he can budge the needle in the White House race.

Obama spoke longer during the 90-minute showdown in Denver on Wednesday, but the Republican challenger landed more blows against an often-subdued president in their first of three debates ahead of the November 6 vote.

Afghan President Hamid Karzai pledged Thursday that he would step down as required by the constitution at the end of his second term in 2014 and that nothing would prevent presidential elections being held.

The election coincides with the scheduled withdrawal of NATO forces from Afghanistan and questions have been raised about whether the security situation could make it impossible for the vote to go ahead.

A U.S. judge formally ordered Hizbullah, Iran, al-Qaida and several other defendants Wednesday to pay $6 billion compensation to the victims of September 11, 2001, in a largely symbolic ruling.

Although Iran denies any connection to 9/11, it was included in the list of alleged culprits by the U.S. District Court in New York, along with Hizbullah, Afghanistan's Taliban guerrillas and al-Qaida, which took credit for the massive terror attack.

Iranian police on Wednesday cracked down on illegal money changers in Tehran, witnesses said, in an apparent bid to halt a dramatic plunge in the value of Iran's currency this week.

Unlicensed vendors who usually walk the streets in the capital's central Ferdowsi area buying and selling small amounts of dollars were rounded up and arrested, witnesses said.

North Korea has dropped thousands of propaganda leaflets attacking South Korea across their heavily militarized border for the second time this year, the South's defense ministry said Tuesday.

South Korean soldiers have collected about 17,000 leaflets, which were floated by balloon over the frontier on Saturday, a ministry spokesman said.

White House hopeful Mitt Romney renewed his attacks on Barack Obama's foreign policies Saturday, blaming the president's "passivity and denial" for sewing chaos in the Middle East.

The Republican nominee took Obama to task for saying unrest and violence were "bumps in the road," adding that such a "casual assessment of shocking events reveals that the president really doesn't understand the gravity of the challenges that we face in the broader Middle East."

Iran on Saturday slammed the United States for removing an exiled Iranian opposition group from its blacklist of designated terror groups, accusing Washington of "double standards" in dealing with terrorism, according to state media.

The de-listing of the People's Mujahedeen of Iran, or Mujahedeen-e-Khalq (MEK), was announced on Friday, ending a complex legal battle fought through U.S. and European courts.

The opposition People's Mujahedeen of Iran welcomed Friday's U.S. decision to strike the group from its terror list and vowed to step up its international campaign against the Tehran regime.

Maryam Rajavi, leader of the group also known as the Mujahedeen-e-Khalq, "welcomed and appreciated" U.S. Secretary of State Hillary Clinton's decision to delist the movement, a statement said.

The United States warned on Saturday that U.S. women Christian missionaries in mainly Muslim Egypt face threats of terror attacks and urged vigilance.

"The embassy has credible information suggesting terrorist interest in targeting U.S. female missionaries in Egypt," the American mission in Cairo said in a statement on its website.