WASHINGTON -- As US forces continue to provide air support for Libyan rebels, observers are asking what makes the embattled North African country different from any other nations of similar situation.

Indeed, the US mission in Libya is aimed at enforcing UN Security Council Resolution 1973, which calls for the establishment of a no-fly zone to protect civilians from attacks.

Some observers, however, ask why the United States has not taken issue with Syria or the Ivory Coast, for example.

What is the criteria for US intervention?

In an interview on Sunday, US Secretary of States Hilary Clinton indicated that, in the eyes of the Obama administration, Gaddafi's actions have crossed the line.

"There's a difference between calling out aircraft and indiscriminately strafing and bombing your own cities than police actions which frankly have exceeded the use of force that any of us would want to see," she said on CBS' "Face the Nation."

"The situation in Libya, which engendered so much concern from around the international community, had a leader who used military force against the protesters from one end of his country to the other," she said of Gaddafi's supposed actions.

The no-fly mission took place while unrest swept through the Arab world, toppling governments in Tunisia and Egypt along the way. Turmoil in Libya erupted not long after Egyptians clogged Cairo's Tahrir Square and ended the decades-long rule of Egyptian President Hosni Mubarak.

Recent days have seen Libyan rebels advance. With the help of international air strikes, rebel fighters took two key port towns and re-gained ground that had been previously lost to Gaddafi's army.

Aside from Clinton's criteria, some analysts said Obama is going after Gaddafi because defeating him is within the range of possibilities.

"Why Libya? As compared with other countries in North Africa and the Middle East, Libya is low-hanging fruit," said Malou Innocent, foreign policy analyst at the Cato Institute.

"Colonel Gaddafi is at the end of his rope, many of those in his inner circle have already defected, and the government lacks political control over a substantial portion of its territory," she said.

A Loss of US Credibility?

Other experts said the United States would have lost credibility if it had allowed the embattled Libyan leader to attack protesters using military hardware, as media have reported.

Ralf Fuecks, co-President at Germany's Heinrich Boll Foundation, said that US inaction would have dealt a heavy blow to the remaining political credibility of the United States in Europe and the Middle East, and would have been a setback for democratic movements in the Arab world. It also would have created more refugees, he said at a panel discussion on Tuesday at the New America Foundation.

Meanwhile, a Gallup poll released on Tuesday indicated that three in four Americans favor some sort of involvement in Libya, although twenty-two percent think the United States should withdraw entirely. Americans are split over what the goal should be, with 45 percent in favor of enforcing the no-fly zone and 44 percent supporting an expansion of the mission to remove Gaddafi from power.

US Goals are Vague

In spite of those numbers, many analysts argue that Obama's goals in the war ravaged country are vague. While Obama has called for an end to the Gaddafi government, the US president also said he will not deploy ground troops. But enforcing a no-fly zone alone is unlikely to unseat the Libyan leader, some analysts argued.

Moreover, some experts believe this is more an issue for those with interests in Libya, such as Italy and France. In contrast, Libya represents no core interest for the United States.

Other analysts said it is time to start planning for a post-Gaddafi era.

"When you look at change and you look at protest that is happening in the street, you need to look at the many downstream consequences," said Steve Clemons, senior fellow at the New America Foundation, at Tuesday's panel discussion.

"Those downstream consequences matter," he said.