As Yemen's future hangs on a thread, some countries are paying closer attention than others.
After a decade of fighting the central government in Yemen's northern provinces, the Iranian-backed Houthi Zaidi Shiite rebels took over the Yemeni capital of Sanaa last September. Last month, Yemeni president Abu-Rabbu Mansour Hadi fled the capital to the southern coastal city of Aden.
On Sunday, the Houthis took over the country's third largest city of Taiz and its airport.
On Monday night, Houthi fighters took control of the Red Sea port of Al-Makha, only 80 km away from the Bab El-Mandab Strait, on the vital maritime route, via the Suez Canal, between the Indian Ocean and the Mediterranean Sea.
On Monday, Yemeni foreign minister Riyadh Yaseen called for Gulf Arab military intervention in Yemen to stop territorial advances by Houthi fighters opposed to president Hadi.
Saudi foreign minister Saud al-Faisal said on Monday that Gulf Arab countries would take necessary measures to protect the region against "aggression" by the Houthi group if a peaceful solution could not be found, according to Reuters.
Prince Saud asserted that Saudi Arabia, which shares a 1,000-mile border with Yemen, opposed Iranian "interference" in the country.
But are Saudi Arabia or Iran likely to stage a military intervention in Yemen?
Saudi or Iranian intervention?
Medhat El-Zahed, an expert on Yemeni affairs, ruled out that a military intervention would take place, and added that no ground operation would be launched unless the Houthis attempted to control the Bab El-Mandeb strait.
“The Houthi forces would be crossing a red line if they attempted to control the Bab El-Mandab Strait," he said. "They would be out of their mind, because then international forces and Arab forces would take action... It's an international waterway.”
Bab El-Mandab connects the Red Sea and the Gulf of Aden. Its strategic importance increased after the Suez Canal was built, as it became part of an international waterway linking the Indian Ocean to the Mediterranean Sea.
In February, the head of Egypt's Suez Canal Authority said that his country would send troops to Yemen if the Houthis attempted to block Bab Al-Mandab.
If Bab El-Mandab was not threatened, El-Zahed said that Arab countries, and Arabian Gulf states in particular, would most likely only intervene in Yemen by supporting Yemeni forces logistically, whether by providing weapons to the Yemeni army or supporting it with satellite images or airstrikes.
Mohamed Abbas, editor-in-chief of the Iranian Selections publication at the Ahram Centre for Political and Strategic Studies, seemed to agree. He said that neither Iran nor Saudi Arabia would be directly involved in a military intervention.
El-Zahed said that Saudi forces would struggle if they became directly involved, as it would be very hard to fight on Yemeni land, especially against the Houthis who are well-trained in guerilla warfare.
In 2009, Saudi forces attacked 30 Houthi rebels attempting to cross the border into Saudi Arabia at Jebel Kaab Jaber, north of Jebel El-Dukhan, the Saudi Gazette reported.
Houthis were very strong at the time, and were able to make the forces of former president Ali Abdallah Saleh and Saudi forces think twice before launching full-ground operations, said El-Zahed.
“The Houthis will lose their grip on the areas they control if the Yemeni people protest against them in these areas,” El Zahed added.
In Taiz, on Tuesday, soldiers and Houthi gunmen killed at least four demonstrators protesting the Houthi take-over of the city, according to Reuters.
El- Zahed added that Iran would have to consider that, were any Iranian military intervention to backfire, not only Arab forces but also the whole international community would then stand against them.
Iran considers itself to be the leader of the Shiite world in the Middle East, while Saudi Arabia considers itself the leader of the Sunni world. In order to prove themselves as the strongest superpower in the region, Iran and Saudi Arabia have sponsored a series of proxy wars across the Middle East, in Iraq, Syria, Lebanon, Bahrain and Yemen.
Abbas said that a proxy war in Yemen would not only be between Iran and Saudi Arabia, but also between Iran and all Gulf and Arab countries, including Egypt.
Abbas concluded that Saudi-Iranian rivalry was not the reason behind division in Yemen. Instead, it was Tehran's choice to support the Houthis, rather than back Yemeni president Hadi.