The vice president expressed concern over the safety of U.S. diplomats amid wave of anti-American protests in Muslim world.

Republican senators introduced a bill Thursday that would require an investigation into the attacks on the United States this week.

Sens. Jim DeMint (R-S.C.) and Bob Corker (R-Tenn.) introduced S. 3551, which would require investigations into and a report on the Sept. 11-13, 2012, attacks on the United States missions in Libya, Egypt and Yemen.

The chairwoman of the Senate Intelligence Committee on Thursday applauded reports that federal authorities are looking into who's behind a U.S.-made anti-Islam video that has sparked protests across the Middle East.

“I'm very pleased to learn ... that people have been arrested” in conjunction with the murder of four State Department officials in Libya, Sen. Dianne Feinstein (D-Calif.) told CNN's Wolf Blitzer. “And I believe an investigation is going on in this country concerning the individual who did this very obnoxious, 12-minute preview of some very stupid movie and wrong-headed movie. 

“He may well not be who he is claimed to be either. So we're going to have to find out a lot about what happened.”

Libyan authorities have reportedly arrested four people in connection with Tuesday's attack in Benghazi.

Democrats and Republicans are appalled by Egyptian President Mohamed Morsi's weak response to violence at the U.S. embassy in Cairo.

Sen. Rand Paul (R-Ky.) tried to tie his bill to end all aid to Pakistan, Libya and Egypt to the veterans’ jobs bill and pass it by unanimous consent.

Sen. John Kerry (D-Mass.) stopped the measure from passing and called Paul's move "arrogant" and dangerous.

The Treasury Department announced on Thursday additional sanctions against Hezbollah's leadership in Lebanon for its support of the Syrian government. 

The sanctions are being leveled against Hasan Nasrallah, Hezbollah's secretary general, and Mustafa Badr Al-Din and Talal Hamiyah, two senior terrorist leaders of Hezbollah, for the group's active support of the regime of Syrian President Bashar Assad, as well as its role in terrorist activities.

“By aiding Assad’s violent campaign against the Syrian people and working to support a regime that will inevitably fall, Hizballah’s ongoing activity undermines regional stability and poses a direct threat to Lebanon’s security,” said David Cohen, under secretary for Terrorism and Financial Intelligence. 

Yemen’s president has apologized to President Obama over the storming of the U.S. Embassy in Sanaa, the Yemeni capital, The Associated Press reports.

President Abed Rabbo Mansour Hadi also ordered an investigation into the riot, which caused no deaths among U.S. personnel. Rioters swarmed into the compound, tore down the American flag and replaced it with a banner that declared “There is no God but Allah.” In addition, rioters removed signs from the compound, set tires ablaze and pelted the crowd with rocks, according to the AP.

Yemeni security forces that rushed to the scene fired into the air and used tear gas to push the rioters out of the compound and disperse the crowd.

The secretary of State called the controversial video "disgusting and reprehensible;" says there is no justification for attacks on Americans.