A landmark nuclear arms treaty shows its age

March 5 marked the 50th anniversary of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) going into force.

Why it matters: While the number of atomic warheads in the world has fallen considerably since the darkest days of the Cold War, the club of nuclear-armed countries has expanded. With countries including the U.S. updating their nuclear arsenals and arms control treaties in danger of collapsing, many experts believe the risk of nuclear conflict is rising.

Flashback: In the early days of the Cold War, it seemed inevitable that we would face "a world in which 15 or 20 or 25 nations may have [nuclear] weapons," as President John F. Kennedy said in 1963.

• That didn't happen thanks to renewed arms control efforts in the 1960s that led to the signing of the NPT, under which states that lacked nuclear weapons pledged not to acquire them and existing nuclear powers committed to eventual disarmament.
• Another factor was Washington's willingness to extend its nuclear umbrella to its allies so that they didn't need to develop their own nuclear programs.

Yes, but: More recently that commitment has wavered, as former U.S. ambassador to NATO Ivo Daalder wrote in the New York Times.

• Russia has shown its willingness to use force in Ukraine, while North Korea has defied Washington in developing a growing nuclear program. Last year the Trump administration withdrew from a treaty banning short-range nuclear missiles.
• The New START Treaty between the U.S. and Russia is set to expire in less than a year. If it isn't extended, it would signal that for the first time in more than four decades "there is no arms control regime in the world," as Sen. Jack Reed said in a congressional hearing last month.

The bottom line: The NPT was one of the first steps the world took to reduce the risk of a global nuclear holocaust. If we forget its lessons, we will be risking our future.

Editor's note: The photo in this story has been changed to depict the USS Arizona Memorial