An Ethiopian government official acknowledged for the first time on Friday that a small force had already rolled across the border and was carrying out reconnaissance missions ahead of a full deployment that would last "weeks". "We are looking at a brief period of time, weeks. We don't want our deployment to be used for propaganda by the extremists," the official told Reuters, declining to be named. "The aim is to support (Somalia's) Transitional Federal Government troops and their allies to expand their control in the south of Somalia and pull back," he added. Head of the regional IGAD bloc, Mahboub Maalim, said Ethiopia had promised to "assist in the peace and stabilisation activities" ongoing in Somalia. Kenya has leaned heavily on Ethiopia to send a force to join the assault against the al Shabaab rebels. Ethiopian troops are unlikely to stray far this time, aware their last intervention in 2006-2009 to flush out another group was a rallying call for the militants. Kenya too has stressed it will leave Somalia once it has dismantled al Shabaab's network and seized strongholds that provide the insurgents a financial lifeline, potentially leaving a void for former warlords to step into. Somalia is a hotspot in the global war against militant. But in the two decades since warlords and then insurgents reduced its government to impotence, a string of foreign forces, including American, have failed to bring order. "The Ethiopians can be none too happy with the state of affairs," said J. Peter Pham, Africa director with US think-tank the Atlantic Council. "The Kenyans, having foolishly charged in with apparently little thought as to realistic strategic objectives are now bogged down and need an additional front opened against al Shabaab to relieve the pressure on them," he said. Kenyan forces crossed into Somalia nearly six weeks ago in an incursion designed to dismantle the militants' network. While they initially advanced smoothly on rebel strongholds in southern Somalia, the Kenyan campaign has stalled as al Shabaab fighters melt into the population, while heavy rains and muddy terrain swamp its forces.