Chuck Hagel will resign as US defence secretary after a request from President Barack Obama to step down, US media report. <br /> <br />Mr Hagel, 68, a Vietnam war veteran and former senator, became defence secretary in 2013. <br /> <br />He is reportedly stepping down amid a shift in US military strategy to fight Islamic State (IS), the New York Times first reported. <br />Mr Hagel was a harsh critic of the handling of the Iraq war.
