Kenyan army spokesman Col Cyrus Oguna said a joint operation of Kenyan and Somali government troops was launched overnight and was "basically amphibious".
"We cannot give casualty figures at the moment, the damage has not been assessed, but I can tell you our forces are already in Kismayo."
More top news
Talks to restore the Northern Ireland Assembly are set to begin on Monday.
The fallout from the General Election continues to lead most of the nation’s front pages on Monday.
Monday will see a mixture of sunshine and showers depending on where you are in the country.