Kenyan military forces are facing heavy rains and muddy terrain as they advance into at least two areas of neighboring Somalia in an effort to hunt down members of the militant Islamist group al-Shabab.

Kenyan troops are reported to be near the al-Shabab-controlled town Afmadow in Somalia's Jubba region, where residents are said to have been fleeing in fear of a battle.

Officials and witnesses told VOA on Tuesday that Kenyan troops, backed by helicopters, had also passed through the Somali border town of El-Waq and advanced to Somalia's Gedo region.

In the Somali capital Mogadishu on Tuesday, Kenyan and Somali government officials pledged to carry out “coordinated pre-emptive action” against “armed elements” that threaten both countries. The agreement appeared to limit Kenyan military action to Somalia's Lower Jubba region.

A suicide car bomb on Tuesday killed at least five people and wounded nine others near Somalia's foreign ministry, where the high-level meeting was taking place. There has been no claim of responsibility for the attack.

Meanwhile, Kenyan police are stepping up security measures after al-Shabab promised on Monday to attack Kenyan targets unless the government withdraws its troops from Somali territory.

Kenya sent an unknown number of troops across the border into Somalia in recent days, in what it called a “pursuit operation” against al-Qaida-linked al-Shabab.

Kenyan officials blame al-Shabab for the death of one tourist and the kidnapping of four others on Kenyan territory.

Al-Shabab has denied responsibility for the abductions, and is calling on Somalis to defend against what it says are Kenyan “aggressors” and “occupiers.”

The last country to invade Somalia was Ethiopia, which deployed troops in 2006 to oust Islamist militants who had briefly taken over the capital. Al-Shabab emerged as the main group fighting the Ethiopians, who withdrew at the beginning of 2009.