"Nuclear weapons are an existential threat to humanity," Ban said in an informal briefing to the UN General Assembly.
"Countries that regard their security as a matter of retaining or attaining nuclear weapons are only increasing risk -- their own and the world," he said.
The Secretary General said that the risks multiply with the emergence of violent and unaccountable non-state actors.
According to him, the threat posed by nuclear weapons is omnipresent yet attracts global attention only intermittently.
"Eight days ago, the test of a nuclear weapon by the Democratic People's Republic of Korea provided the latest such jolt. This was a destabilising act that violates Security Council resolutions and imperils collective security.
"It underscores yet again the general risk of nuclear weapons - and the specific dangers of the DPRK, which faces severe developmental and human rights challenges," he said.
But the Comprehensive Nuclear-Test-Ban Treaty (CTBT) has still not entered into force, he said. Negotiations on a ban on the production of fissile material have not begun. And some nuclear-armed states are spending massively to modernise their arsenals, Ban said.
Ban said he would present a Plan of Action to Prevent Violent Extremism.
"Our challenge is to defeat Daesh (IS), Boko Haram, al-Shabaab, al Qaeda and other such groups - without defeating ourselves through counter-productive approaches that fuel the extremism we are trying to extinguish. Well-calibrated, security-based counter-terrorism measures remain essential. But human rights must be at the forefront of our response," he said.
"My peace operations initiative sets out a comprehensive action agenda to strengthen United Nations peace and security tools, including through closer peacekeeping partnerships with regional organisations and local communities," he said.
Ban said if 2015 was a year of global sustainable development action, 2016 must be a year of national SDG traction.
"These towering achievements point the world in promising new directions. At a time of massive humanitarian need, they give hope that we can overcome global divisions in the name of the common good," he said.
