The United States is expanding its military role in Yemen. Yemeni officials say U.S. forces assisted Yemeni troops in launching a wide air and land offensive against militant groups in the south of the country.
The United States has a long history of advising and assisting Yemen in that country's fight against the al-Qaida in the Arabian Peninsula group.
That cooperation was suspended during Yemen's recent political turmoil, in which violent protests led to the exit of longtime ruler Ali Abdullah Saleh.
With new President Abd Rabbou Mansur Hadi taking steps to restore constitutional order and signs terrorist activity is growing in the country, U.S. help has resumed with the Pentagon recently announcing the return of a limited number of U.S. troops to train and assist Yemeni forces.
Defense Secretary Leon Panetta told reporters a recently foiled terrorist plot to bring down a U.S. commercial airplane underscores the need for U.S. forces to intensify their hunt for al-Qaida operatives wherever they are and wherever they try to hide.
"The recent threat that concerned all Americans about the possibility of another effort to take down an American airliner has come out of Yemen and it is for that reason that we will continue to take all of the steps necessary to try to go after those who would threaten our country and threaten the safety of American people," said Panetta.
Panetta and other officials are not giving specifics on the operations under way in Yemen, but they say the cooperation is growing. The Defense Secretary rules out sending in U.S. ground forces.
"There is no consideration of that," Panetta added. "Our operations now are directed with the Yemenis going after al-Qaida."
Yemeni officials say the most recent assault on militants was carried out by Yemeni warplanes and troops with direct guidance from a small number of U.S. personnel in the country. Officials outside the Pentagon, speaking anonymously, say U.S. forces are helping Yemenis with intelligence, including satellite imagery, pictures from drones and other means to help them locate targets.
The United States military's aim is to build the Yemenis' capacity, an approach consistent with the Obama administration's defense strategy that calls for a smaller U.S. footprint in international operations.
Defense analyst Anthony Cordesman at the Center for Strategic and International Studies research group says that is accomplished with special operations forces and others who are sent in to work closely with the Yemenis.
"They are really partners," Cordesman explained. "They work with forces that are not used to this kind of mission that may be experiencing serious problems in terms of political leadership, and direction in a country that is going [through] the kind of turmoil that Yemen has. These partners effectively are capable of taking units that do not have the same level of experience, basically guiding the officers, guiding the unit, helping it really perform the mission. At what point are you leading and at what point are you partnering, this is sort of an exercise of semantics."
The operations are part of Washington's broader effort to bring stability to Yemen and stamp out al-Qaida in a region the United States sees as strategically important due to its history as a haven for terrorists, and its proximity to shipping lanes leading to the Suez Canal, the Red Sea and the Persian Gulf.
The White House last month gave the Pentagon and the Central Intelligence Agency wider authority to carry out drone strikes against militants in Yemen.
It has also bolstered its support of President Hadi, who analysts say has shown a greater willingness to work more directly with U.S. forces than the previous government. This week, President Barack Obama signed an executive order to freeze assets of those who threaten Yemen's political transition process.
Sources say the U.S. military's efforts in Yemen are being carried out on a much smaller budget than before cooperation was suspended last year, a reflection of the Pentagon's new financial constraints in the face of severe cuts.