Australian Prime Minister Julia Gillard has welcomed Afghanistan's decision to begin taking over security in parts of the country. In a statement, Gillard said the transition is a process, not an event, and Australia and its International Security Assistance Force partners will continue to support Afghanistan as the mission progresses. She said the key challenge for the Afghan government and the Force is to ensure that transition is sustainable and irreversible. Gillard said Australia, which has around 1,550 troops in Afghanistan and has lost 23 soldiers in the conflict since 2001, will continue to train the Fourth Brigade of the Afghan National Army in the southern province of Uruzgan. On Tuesday, Afghan president Hamid Karzai announced that the transfer of power from NATO-led forces will begin in July and includes parts of the Helmand province in the south. The transfer is the first step towards the withdrawal of foreign troops from Afghanistan by the end of 2014.