A suspected suicide bomber killed himself and wounded nine people when he detonated a grenade near a military air base in Nairobi on Friday, police said, in the latest such attack since Kenya's military foray into neighbouring Somalia.The incident occurred in a Somali-dominated area, and police said the attacker had intended to blow up a group of soldiers near the perimeter of the air base.All but one of the wounded were civilian bystanders, police said."The person was a suicide attacker, he blew up what we believe was a grenade and we presume he was targeting the air base perimeter," Nicholas Kamwende, head of the criminal investigations department in Nairobi, told Reuters."Nine other people were injured," he added.The attack came shortly before a visit to Kenya by US Secretary of State Hillary Clinton to Africa, whose trip in part is intended to strengthen US security ties in the face of growing threats from Islamist militants.After travelling from Uganda, Clinton is expected to meet Kenya's President Mwai Kibaki in Nairobi on Saturday and, later, Somali President Sheikh Sharif Ahmed.Nairobi has blamed the series of attacks on Somalia's al-Qaeda-linked al Shabaab, which has threatened to retaliate since the east African economic powerhouse's military pursued the Islamists into Somalia in October.Other grenade attacks have hit the capital and the coastal city of Mombasa, threatening Kenya's lucrative tourism sector.Two Iranians are facing charges in court after they were arrested in June in connection with chemicals police suspected were destined to be used to make explosives.