Updated

At least 20 troops from a Saudi-led Arab coalition, including Yemeni expatriates in shorts, landed Sunday in Yemen's southern coastal city of Aden on a "reconnaissance" mission amid a fierce offensive by Shiite rebels and their allies there, Yemeni military officials said.

The objective of the landing, which Saudi officials declined to immediately comment on, was not clear. However, military and security officials repeatedly have said that a ground operation would follow a Saudi-led airstrike campaign after the military capabilities of the Houthi rebels and their allies had been sufficiently weakened.

The Yemeni military officials and witnesses reached in Aden said the black-clad and masked coalition troops landed in a central area between Aden's neighborhood of al-Mansoura and the airport. They said helicopter gunships hovered above the landing area.

The officials later said the troops used at least four vehicles to move around in Aden and that they included Yemenis serving in the armed and security forces of some Gulf Arab members of the coalition. Those Yemenis, according to the officials and the witnesses, may have served as guides to foreign troops who came ashore with them.

They said the troops carried assault rifles and took photos of the areas they toured.

It was not immediately clear whether the troops were ferried to Aden by helicopters taking off from coalition navy ships off the coast of Yemen or travelled to shore in speed boats.

There were no reports of fighting between the Arab troops and the Iranian-allied Houthis or their supporters-- army troops loyal to former President Ali Abdullah Saleh. The insurgents have been fighting militiamen loyal to President Abed Rabbo Mansour Hadi for weeks over control of Aden, a strategic port city on the Arabian Sea.

Hadi fled Aden to neighboring Saudi Arabia in March, just a few weeks after he had fled the capital, Sanaa, which was captured by the Houthis in September.

The officials, who include a top army commander based in Aden and loyal to Hadi, spoke on condition of anonymity as they weren't authorized to brief journalists. Residents who witnessed the landing spoke on condition of anonymity for fear of reprisals.

The landing came on a day when the coalition staged renewed airstrikes against positions of the Houthis and their allies in Aden, now nearly a daily occurrence and the main reason why pro-Hadi forces continue to hold most of the city.

The landing also came one day after Egyptian President Abdel-Fattah el-Sissi discussed Yemen with Saudi leadership during a brief visit to the oil-rich kingdom. Egypt, the most populous Arab state, is a key member of the coalition and has been touted as a likely participant in any ground operation in Yemen.

Details of the talks have not been disclosed by Cairo or Riyadh.