Operation Sovereign Borders (OSB) is a border protection operation led by the Australian Defence Force, aimed at stopping maritime arrivals of asylum seekers to Australia. The operation is the outcome of a 2013 federal election policy of the Coalition, which commenced on 18 September 2013 after the election of the Abbott government. The operation has implemented a "zero tolerance" posture towards what it has termed "Illegal Maritime Arrivals" − a change in terminology from the previous government's "Irregular Maritime Arrivals" − in Australia, in conjunction with mandatory detention in offshore detention facilities.