Barack Obama has become the first incumbent US president to visit Hiroshima, laying a wreath at the site of the world’s first atomic bombing in a gesture Tokyo and Washington hope will showcase their alliance and invigorate efforts to end nuclear arms.

South Korea and Japan have agreed to resolve the issue of ‘comfort women’, as those who were forced to work in Japan’s wartime brothels were euphemistically known. The issue has long plagued ties between the neighbours.