US President Barack Obama has announced in the United Nations summit a pledge by 50 nations to take in 360,000 refugees from war-torn countries this year. Mr Obama told the summit that the refugee crisis was "a test of our international system where all nations ought to share in our collective responsibilities, because the vast majority of refugees are hosted by just 10 countries." About 21 million refugees have been forced to flee their countries due to conflict or persecution, the UN says.