In a victory for disarmament and peace campaigners—and all of humanity—a treaty banning nuclear weapons entered into force on Friday, a development that experts and activists hailed as \u0022groundbreaking\u0022 even though the pact lacks support from the world\u0026#039;s nine nuclear powers.\u0022Ever since the atomic bombings of Hiroshima and Nagasaki, citizens the world over have petitioned and protested for a permanent ban on nuclear weapons.\u0022—Beatrice Fihn, ICAN\u0022Today we reach a major milestone on the road to a more peaceful and secure world, free from the ultimate menace of nuclear war,\u0022 said Beatrice Fihn, executive director of the International Campaign to Abolish Nuclear Weapons (ICAN), at a United Nations ceremony on Friday marking the momentous occasion.ICAN was awarded the 2017 Nobel Peace Prize for its efforts \u0022to draw attention to the catastrophic humanitarian consequences of any use of nuclear weapons\u0022 and advance the ban.\u0022Ever since the atomic bombings of Hiroshima and Nagasaki, citizens the world over have petitioned and protested for a permanent ban on nuclear weapons. That ban—long imagined, long sought—is now, finally, in force,\u0022 Fihn noted Friday, calling the historic treaty a \u0022monumental accomplishment.\u0022GOOD MORNING WORLD! Today, nuclear weapons are banned. There’s no going back from this point, the #nuclearban will only grow stronger from now on. The ban is the future. pic.twitter.com/Fpex7qFopW— Beatrice Fihn (@BeaFihn) January 22, 2021During the event, Cambodia became the 52nd state party to the Treaty on the Prohibition of Nuclear Weapons (TPNW), which was adopted in July 2017 and opened for signature that September. It took over three years for the treaty to gain the requisite 50 ratifications to enter into force.Despite opposition from nuclear states, particularly the U.S. under the Trump administration, Honduras became the 50th state to ratify the TPNW in October. States party to the agreement cannot develop, test, produce, acquire, possess, stockpile, use, or threaten to use nuclear weapons.\u0022Nuclear weapons pose growing dangers and the world needs urgent action to ensure their elimination and prevent the catastrophic human and environmental consequences any use would cause.\u0022—U.N. Secretary-General António Guterres\u0022Some will seek to downplay the historical significance of this moment—those intent on preserving the status quo, who feel strong wielding these instruments of mass murder; or those who profit from their production,\u0022 Fihn said Friday. \u0022But their voices are soft whimpers amid the loud chorus of support for this crucial new piece of international law.\u0022Fihn called on states that haven\u0026#039;t yet ratified the TPNW to do so and those that support their allies\u0026#039; nuclear weapons to \u0022stop now.\u0022 She also appealed directly to nuclear-armed states (China, France, India, Israel, North Korea, Pakistan, Russia, the United Kingdom, and the United States), saying: \u0022Your weapons are now banned. Permanently. You are on the wrong side of international law, the wrong side of history, and the wrong side of humanity. It\u0026#039;s time to consign your awful bombs to the dustbin of history.\u0022U.N. Secretary-General António Guterres welcomed the ban with a video message in which he declared, \u0022Nuclear weapons pose growing dangers and the world needs urgent action to ensure their elimination and prevent the catastrophic human and environmental consequences any use would cause.\u0022Today, the Treaty on the Prohibition of Nuclear Weapons enters into force.This is a major step toward a world free of nuclear weapons.I call on all countries to work together to realize this vision, for our common security and collective safety. pic.twitter.com/ybDamSdCZs— António Guterres (@antonioguterres) January 22, 2021Guterres commended states that have ratified the TPNW and recognized the contributions of survivors of nuclear explosions and nuclear tests who \u0022offered tragic testimonies and were a moral force behind the treaty,\u0022 adding that \u0022entry into force is a tribute to their enduring advocacy.\u0022The U.N. chief also said that he looks forward to \u0022carrying out the functions assigned by the treaty, including in preparation for the first Meeting of States Parties,\u0022 and reiterated that \u0022the elimination of nuclear weapons remains the highest disarmament priority of the United Nations.\u0022Other peace advocates and experts also added their voices to the celebration.\u0022This treaty—the result of more than 75 years of work—sends a clear signal that nuclear weapons are unacceptable from a moral, humanitarian, and now a legal point of view,\u0022 said\u0026nbsp;Peter Maurer, president of the International Committee of the Red Cross. \u0022It sets in motion even higher legal barriers and an even greater stigmatization of nuclear warheads than already exists. It allows us to imagine a world free from these inhumane weapons as an achievable goal.\u0022Pope Francis, in a tweet welcomed by ICAN, encouraged all states and people \u0022to work decisively toward promoting conditions necessary for a world without nuclear weapons, contributing to the advancement of #peace and multilateral cooperation which humanity greatly needs today.\u0022Thank you @Pontifex! Today, Pope Francis welcomes the #nuclearban treaty’s entry into force and calls on all people and states to work ‘with determination’ to reach a world without nuclear weapons. https://t.co/LHKdDQgHZg— ICAN (@nuclearban) January 22, 2021In a statement anticipating the treaty\u0026#039;s entry into force, Daryl G. Kimball, executive director of the U.S.-based Arms Control Association, said that \u0022the TPNW is a powerful reminder that for the majority of the world\u0026#039;s states, nuclear weapons—and policies that threaten their use for any reason—are immoral, dangerous, and unsustainable.\u0022Tom Countryman, former U.S. assistant secretary of state for international security and nonproliferation, now serves as chair of the board of the Arms Control Association. He urged U.S. President Joe Biden, who took office on Wednesday, to pursue a different path from his predecessor—whose administration tried to argue that the TPNW \u0022is dangerous\u0022 to the 1968 Nuclear Nonproliferation Treaty (NPT).\u0022Rather than adopt\u0026nbsp;the Trump administration\u0026#039;s misguided criticism of the TPNW as a threat to the NPT and repeat\u0026nbsp;its clumsy attempt to get states [to] un-sign the treaty,\u0022 Countryman said, \u0022the incoming Biden administration should make it clear that the United States views the TPNW a good faith effort by the majority of the world\u0026#039;s nations to fulfill their own NPT-related disarmament obligations and help build the legal framework for the eventual elimination of nuclear weapons.\u0022William J. Perry served as undersecretary of defense for research and engineering in the Carter administration and secretary of defense in the Clinton administration. Now the chair of the Bulletin of the Atomic Scientists\u0026#039; Board of Sponsors, Perry offered Biden similar advice:\u0022The Treaty on the Prohibition of Nuclear Weapons is a significant step forward, toward the future we imagined 14 years ago,\u0022 @SecDef19 writes, referencing his iconic piece with George Shultz, Henry Kissinger, and Sam Nunn.— Alicia Sanders-Zakre (@azakre) January 22, 2021Nearly a year ago, the Bulletin set its Doomsday Clock at 100 seconds to midnight, \u0022closer than ever before to apocalypse.\u0022 The decades-old symbol of the threat posed by nuclear weaponry and, more recently, the human-caused climate crisis is set to be updated again next week.