Protestors took to the streets Tuesday and top American officials expressed concern as a billionaire businessman closely allied with the terrorist group Hizballah emerged as Lebanon's new prime minister.

Hizballah Secretary-General Hassan Nasrallah welcomed Najib Miqati's selection with a warning to the terror group's domestic political foes, warning Lebanese not to "plot against us or backstab us."

Nasrallah seemed to be referring to ousted Prime Minister Sa'ad Hariri, who called the change in power a coup d'etat. "Today, you are an angry people," Hariri said in a televised appeal for calm, "but you are a people responsible about the safety of Lebanon and the common life among Lebanese people. Anger cannot be expressed by cutting off roads, burning tires or infringing the freedom of others, regardless of the motives."

Hizballah triggered the government collapse last week as Hariri met with President Obama. Pro-Hizballah cabinet members resigned to protest Beirut's support for a United Nations special tribunal investigating the 2005 assassination of Hariri's father, former Prime Minister Rafiq Hariri. The tribunal issued a sealed indictment that is expected to name Hizballah officials in connection with the Hariri murder.

In his remarks, Nasrallah made it clear that Sa'ad Hariri's failure to disavow the tribunal led to his ouster. "You went to Washington, made commitments, and plotted against the Resistance and its arms. Even the national dialogue table's aim was to disarm the resistance, but you failed," Nasrallah said. "You asked for the July War on the resistance and you failed. Today, there is the Special Tribunal for Lebanon and it's being employed to get rid of the Resistance, but you will also fail."

Hizballah control could prompt the U.S. to designate Lebanon as a terrorist state, cutting off hundreds of millions of dollars in annual economic and military aid. "A Hizballah-controlled government would clearly have an impact on our bilateral relationship with Lebanon," said Secretary of State Hillary Clinton. "Our bottom lines remain as they always have been. First, we believe that justice must be pursued and impunity for murder ended. We believe in Lebanon's sovereignty and an end to outside interference. So as we see what this new government does, we will judge it accordingly."

U.S. Rep. Sue Myrick, R-N.C., wrote to President Obama Tuesday urging the administration to be more proactive.

Israel also is warily viewing Hizballah's political ascendancy. Vice Prime Minister Silvan Shalom called it a "dangerous development," stating: "This is not just about a terror organization which operates with Iran's support and inspiration anymore, but rather a real sovereign government." Shalom warned it was possible that an "Iranian government" will be established in Lebanon.