KABUL - The Taliban announced the start of their annual spring offensive on Wednesday, dismissing an offer for peace talks by President Ashraf Ghani but pledging to focus on US forces in Afghanistan.The announcement of the Al Khandaq campaign, named after the so-called Battle of the Trench, fought by the Prophet Mohammad to defend the city of Medina in the early days of Islam, marks the symbolic start of the fighting season.But heavy fighting has been going on in different parts of the country and hundreds of people have been killed and wounded in a series of high profile attacks in Kabul since the beginning of the year, despite Ghani's offer in February for peace talks "without preconditions."The Taliban, in their statement on Wednesday, dismissed the peace overtures as a "conspiracy.""Their main effort is to deviate public opinion from the illegitimate foreign occupation of the country, as the Americans have no serious or sincere intentions of bringing the war to an end," the Taliban said.The militants, fighting to restore their version of strict Islamic law to Afghanistan, said the campaign was a response to a more aggressive US military strategy adopted last year, which aims to force the militants into peace talks."Its primary target will be the American invaders and their intelligence agents. Their internal supporters will be dealt with as a secondary target," the Taliban said.