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."
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This defeat for Theresa May matters: it shows the fury among some MPs, notably those who voted to Remain, that they are being ignored.
Theresa May's government has been narrowly defeated in a key Commons vote after a rebellion by Conservative MPs.
Despite temperatures reaching double figures in the south today, it was still a chilly day, with brisk winds.