Pentagon in position to evacuate U.S. Embassy in YemenBy Barbara Starr, CNN Pentagon CorrespondentUpdated 2056 GMT (0456 HKT) January 20, 2015Unrest in Yemen 19 photosSupporters of the separatist Southern Movement flash the victory sign after they seized police security checkpoints on Saturday, January 24 in Ataq, the capital of Shabwa province in Yemen. Policemen were told to give up their weapons and return to their bases, before the militiamen raised flags of the formerly independent South Yemen at the checkpoints. Yemeni President Abdu Rabu Mansour Hadi resigned shortly after his Prime Minister and the Cabinet stepped down -- seismic changes in the country's political scene a day after the government and Houthi rebels had struck a tentative peace deal meant to turmoil. Hide Caption 1 of 19Unrest in Yemen 19 photosUnrest in Yemen – Shiite Huthi rebels fight with Yemeni protesters during a rally against the control of the capital by Huthi rebels on January 24 in the capital Sanaa. Thousands of Yemenis took to the streets of Sanaa in the largest demonstration against Huthis since the Shiite militiamen overran the capital in September. Hide Caption 2 of 19Unrest in Yemen 19 photosHouthi Shiite fighters wearing army uniforms ride on a truck as they patrol a street during a demonstration to show support for their comrades in Sanaa, Yemen, on Friday, January 23. Hide Caption 3 of 19Unrest in Yemen 19 photosHouthis carry coffins of those killed during recent clashes with presidential guard forces in a funeral procession on January 23, in Sanaa, Yemen. Hide Caption 4 of 19Unrest in Yemen 19 photosA Houthi militiaman sits at a tank near the presidential palace in Yemen's capital on Thursday, January 22. The chaos in Yemen is cause for concern far beyond the country's borders. The Yemeni government has been a key U.S. ally in the fight against al Qaeda in the Arabian Peninsula, the Yemen-based terror group. Hide Caption 5 of 19Unrest in Yemen 19 photosArmed members of pro-government militias patrol outside Aden's airport in southern Yemen on January 22.Hide Caption 6 of 19Unrest in Yemen 19 photosHouthi men wearing army uniforms stand guard on a street leading to the presidential palace in Sanaa on Wednesday, January 21. Hide Caption 7 of 19Unrest in Yemen 19 photosA wounded man rests at a hospital in Sanaa on January 21. He was reportedly injured in fierce clashes the previous day.Hide Caption 8 of 19Unrest in Yemen 19 photosA tank is stationed in front of the house of President Abdu Rabu Mansour Hadi on January 21.Hide Caption 9 of 19Unrest in Yemen 19 photosA Houthi rebel mans a checkpoint near the presidential palace on January 21.Hide Caption 10 of 19Unrest in Yemen 19 photosA man walks inside a heavily damaged house near the presidential palace on Tuesday, January 20. Houthi rebels took control of the palace, Yemen's Minister of Information Nadia Sakkaf told CNN, a day after heavy fighting ended in a ceasefire deal.Hide Caption 11 of 19Unrest in Yemen 19 photosA woman walks past closed shops in Sanaa on January 20.Hide Caption 12 of 19Unrest in Yemen 19 photosAn armed member of the Houthi movement stands guard in the streets of Sanaa on January 20. Houthis are Shiite Muslims who have long felt marginalized in Yemen, a majority Sunni Muslim country.Hide Caption 13 of 19Unrest in Yemen 19 photosA man surveys his damaged home in Sanaa on January 20.Hide Caption 14 of 19Unrest in Yemen 19 photosHouthis inspect a damaged mosque in Sanaa on January 20.Hide Caption 15 of 19Unrest in Yemen 19 photosHouthi men raise their weapons during clashes near the presidential palace on Monday, January 19.Hide Caption 16 of 19Unrest in Yemen 19 photosSmoke and flames rise in Sanaa during heavy clashes between presidential guards and Houthi rebels on January 19.Hide Caption 17 of 19Unrest in Yemen 19 photosTribal soldiers protecting the city from Houthi rebels stand guard at the city borders in Marib, Yemen, on January 19.Hide Caption 18 of 19Unrest in Yemen 19 photosHouthi men guard a Sanaa street on January 19.Hide Caption 19 of 19Washington (CNN)Two U.S. Navy warships moved into new positions in the Red Sea late Monday to be ready to evacuate Americans from the US embassy in Yemen if an order comes to do so, CNN has learned. So far, there has been no decision to evacuate the embassy. The USS Iwo Jima and the USS Fort McHenry were moved "because they will be in the best position if asked," by the State Department to evacuate the embassy, a U.S. official with direct knowledge of the planning tells CNN. So far there has been decision to evacuate the embassy, and no request from the State Department for military assistance.If an evacuation is ordered, the first option would be to have embassy personnel drive to the commercial airport in Sanaa and fly out, the official said. But in the wake of an embassy car being fired Tuesday, the safety of the roads in the capital is now being constantly evaluated, the official said. If embassy workers did drive to the airport it is likely some sort of air cover would be provided, under the current plan.Other detailed military planning for various options has been finalized, the official said. Those options would be used if a request for military assistance were made.If helicopters and V-22 aircraft from the ships are sent to Sanaa, it would be a complex operation that could last for several days to fully evacuate "several hundred Americans" from the embassy, the official cautioned. "Nobody should think this would be easy." The military is aware the State Department wants to keep the embassy open as long as possible, the official said, noting that it's a valuable tool to monitor Al Qaeda in Yemen. But behind the scenes the Pentagon is pressing the point that if an evacuation becomes necessary they want to do it before the chaos in Sanaa descends into a 'non permissive environment," akin to combat. For now, the US believes the Houthis are not targeting Americans, but its not clear if that will last.The plan at this point only involves the potential evacuation of State Department personnel. It would be up to State to decide if it wants to extend the potential mission to other Americans in Yemen.More from PoliticsClinton agrees to testify again on BenghaziCNN exclusive: Rand Paul Snapchat interview Congressman: Hillary Clinton agrees to testify to House's Benghazi panelMore from Barbara StarrBergdahl decision expected in days U.S. hits Yemen with drone strike, closes embassy to public amid upheavalWill U.S. advisers move to Iraqi front lines?