Kenya has announced it will intensify its operation against the Al-Shabaab rebel group amid recent attacks in its border areas with Somalia. Chief of Defence Forces General Julius Karangi said Wednesday the troops battling Al-Shabaab militia had been put on high alert during the Christmas season in expectation of more aggressive attacks. \"The soldiers remain on high alert. They will remain on a higher level of alert than before,\" Karangi told journalists, when he visited troops at a military camp in Ishakani, about 4 km from the Somali border and a launching point for the Al-Shabaab operation. The Kenyan Defence Forces (KDF) deployed on land, sea and air have been in hot pursuit of the Al-Shabaab, which has promised revenge attacks. Kenyan officials blame the Islamist group or their sympathizers for a series of recent shootings and bombings in Kenya. The higher alert comes as security forces launched a major crackdown at Dadaab refugee complex Tuesday and Wednesday and arrested two Somali men in connection with recent blasts that killed a policeman and injured two others in Hagardera camp. Acting Dadaab District Commissioner Bernard Ole Kipury said he suspected Al-Shabaab sympathizers were behind the blasts and accused the militants of disguising themselves as refugees to enter the camp, home to more than 450,000 people, mainly Somalis who have fled famine and conflict in their country. He said the authorities had intensified patrols in the camp and would soon be conducting more operations to flush out militants. The explosions were the latest in a spate of grenade and landmine attacks in Kenya\'s northern regions bordering Somalia since its troops crossed into the troubled country. And they came only a week after four people were injured in two separate grenade attacks in the northern Kenyan town of Garissa. On Thursday, the Kenyan navy carried out attacks against Al-Shabaab\'s strongholds of Afmadow and Kismayu on Somalia\'s southern coast. The port of Kismayu has long been used by the militants for military supplies and a key revenue source for financing attacks. Karangi said Kismayu and Afmadow would not remain the only targets. \"Our mandate remains the same, to degrade and ultimately eliminate the Al-Shabaab. The operation includes the actual killing of the Al-Shabaab.\" KDF spokesman Major Emmanuel Chirchir said the air force would intensify its aerial bombardments of Al-Shabaab targets. On Wednesday, two air raids on suspected Al-Shabaab villages in the town of Hosingo, near the Kenyan border, killed a senior Al-Shabaab military commander. The military attack strategy was to seize Kismayu and Afamadow, an operation being delayed by heavy rains in southern Somalia, which slowed the movement of military equipment, the KDF said earlier. The plan was further delayed after the U.S. State Department said it required further study to avoid creating a bigger humanitarian tragedy. Military Operations Commander Colonel Cyrus Oguna said the forces slowed their campaign to address the needs of Somalis and \"avoid antagonizing\" them. Karangi said, once the objective was achieved, the forces would spread out to the rest of Somalia. Meanwhile, police have promised to provide security during the festive season. The authorities also pledged to enhance intelligence operations against local supporters of the rebel group. \"I indeed warn the Al-Shabaab sympathizers that their time is up. We shall catch up with them,\" Karangi said.