Afghan President Ashraf Ghani(R) addresses a joint meeting of Congress on Capitol Hill in Washington D.C., USA - 25/03/2015. U.S. House Speaker John Boehner(R) and U.S. Vice President Joe Biden (L) listen him. Visiting Afghan President Ashraf Ghani on Wednesday warned that extremist groups such as Islamic State (IS) pose a "grave and present danger" to Afghanistan's security transition. Credit : Yin Bogu/CHINE NOUVELLE/SIPA./CHINENOUVELLE_2503.b.004