Nairobi - The governor of northern Kenya's Mandera county on Monday attacked what he called a "hopeless" security situation due to a wave of cross-border attacks by Somalia's al-Shabaab militants.Speaking in the capital Nairobi, Ali Roba said he had survived six attempts on his life - including an ambush of his convoy on Friday - and questioned why Kenyan soldiers were part of an African Union force supporting Somalia's government while leaving their own country unprotected.Mandera, in Kenya's far northeast, borders Somalia and is plagued by insecurity. The area has been the scene of a string of recent attacks by the al-Qaeda-linked militants."We can no longer stand before the public and assure them that the security is being beefed up," he told reporters, describing the situation in the far north as "extremely hopeless" and warning that "residents will do what they have to do" unless the national government stops the attacks.String of attacks"The government has a responsibility to protect the whole country, and there is no need for it to keep soldiers [in Somalia] to protect Somalis instead of protecting Kenyans," he added.In November, Shabaab gunmen held up a bus outside Mandera town, separated passengers according to religion and executed 28 non-Muslims. Ten days later 36 non-Muslim quarry workers were also massacred in the area.Roba's convoy was ambushed on Friday, an attack that left three dead, while a drive-by shooting in Mandera late on Sunday left one dead and three wounded.The Shabaab, who say they are retaliating for Kenya's presence in Somalia, have claimed responsibility for the string of attacks in the region.According to the governor, Shabaab fighters were moving around the border regions in small groups of 15 fighters.Growing unease"We need infantry, we need people who can fight them in the bush," he said, also calling for Mandera county's commissioner - a government appointee responsible for security - to be sacked.The comments are the latest sign of growing unease in Kenya's border region.Following last year's massacres, six trade unions representing doctors, dentists and teachers advised their members to leave the area until the Kenyan government could ensure security.Scores of teachers working in the north also protested in Nairobi last month, demanding a transfer to safer parts of the east African nation.Attacks by the Shabaab in northern Kenya have intensified since Kenya sent troops into Somalia in 2011. Kenyan troops are now a part of an African Union force supporting the Horn of Africa nation's internationally-backed government.The Shabaab was also behind the September 2013 attack on Nairobi's Westgate shopping mall that killed at least 67 people.