The first-ever treaty to ban nuclear weapons entered into force on Friday, hailed as a historic step to rid the world of its deadliest weapons but strongly opposed by the world's nuclear-armed nations. The Treaty on the Prohibition of Nuclear Weapons is now part of international law, culminating a decades-long campaign aimed at preventing a repetition of the U.S. atomic bombings of Hiroshima and Nagasaki at the end of World War II. But getting all nations to ratify the treaty requiring them to never own such weapons seems daunting, if not impossible, in the current global climate. When the treaty was approved by the U.N. General Assembly in July 2017, more than 120 approved it. But none of the nine countries known or believed to possess nuclear weapons the United States, Russia, Britain, China, France, India, Pakistan, North Korea and Israel " supported it and neither did the 30-nation NATO alliance. Nonetheless, Beatrice Fihn, executive director of the International Campaign to Abolish Nuclear Weapons, the 2017 Nobel Peace Prize-winning coalition whose work helped spearhead the treaty, called it "a really big day for international law, for the United Nations and for survivors of Hiroshima and Nagasaki." As of Thursday, Fihn told The Associated Press that 61 countries had ratified the treaty ... and "from Friday, nuclear weapons will be banned by international law" in all those countries.