The Kenyan army says it has destroyed key facilities belonging to al-Shabab militants in the Somali port city Kismayo, the group's largest remaining stronghold.

Army spokesman Cyrus Oguna told VOA Kenyan jets destroyed two sites at an al-Shabab airport on Tuesday.

“One was a warehouse where al-Shabab has been keeping weapons. The other one was an armory, also for keeping ammunition.”

Oguna said the area had long been a logistics center for the al-Qaida-allied group.

Kenyan forces with the African Union and Somali government troops are preparing to launch a major offensive to recapture Kismayo.

The international troops have been stationed about 60 kilometers outside the port city since last week.

Oguna said Kenyan jets fired more than 10 missiles around the city and that the strikes did not result in civilian casualties.

Al-Shabab militants in Kismayo have vowed to fight to the death against pro-government forces.

The militants have used the town's seaport to bring in weapons and other supplies to support their battle against the government.

The extremist group is seeking to impose a hardline form of Sharia throughout Somalia. It once controlled most of southern and central Somalia, but has lost most of its territory to pro-government forces since they launched a major offensive last year.