New York, Dhu-AlQa'dah 29, 1435, Sep 24, 2014, SPA -- The world needs to unite against key global challenges, including terrorism in Iraq and Syria, Russian aggression in Europe and the Ebola outbreak in West Africa, says US President Barack Obama at the United Nations General Assembly, as dpa reported. "We can renew the international system that has enabled so much progress, or allow ourselves to be pulled back by an undertow of instability," he says. "We can reaffirm our collective responsibility to confront global problems, or be swamped by more and more outbreaks of instability." He calls on the UN to renew the purpose of its founding and to joining to "reject the cancer of violent extremism." --SPA 17:24 LOCAL TIME 14:24 GMT www.spa.gov.sa/w