At least 30 people died in a span of 24 hours in shootings and blasts attributed to the militant group.
Somalia's Al-Shabab group has been blamed for killing 12 people in a Kenyan border town, as well as gunning down an intelligence officer and attacking a military base with a suicide truck bomb in Somalia in a series of strikes on Tuesday.
Kenya deployed its army into Somalia in 2011 to hinder Al-Qaeda linked Al-Shabab's bid to overthrow Somalia's Western-backed government and drive out African Mission in Somalia (AMISOM) peacekeepers. Since then, the country has been the scene of numerous assaults by the militant group.
Eleven men and one woman were killed in the 3:30 am (0030 GMT) blast at the Bishar Guesthouse, northeastern Kenya, in the attack in which the militant group said non-Muslims were targeted.
"This attack is part of a series of attacks in which the Mujahideen are hunting down infidels," Al-Shabab's spokesman for military operation, Abdiasis Abu Musab said.
The attack took place hours after fighters from the group shot dead an intelligence officer in Somalia's capital Mogadishu.
Later in the day, the spokesman said the militants were behind a truck bomb that rammed into an AMISOM base in the Somali town of Beledweyne, north of Mogadishu. He said 17 soldiers from Djibouti were killed in the expl.
Reinforcement from a nearby base then rushed to the camp and swiftly brought the situation under control, according to AMISOM, which is battling the rebels in support of the government. "The terrorists were all killed," it said on Twitter.
The AMISOM peacekeepers are made up of soldiers from Kenya, Djibouti, Uganda, Ethiopia and other African nations.