The U.S. bishops have urged more action to ensure nuclear disarmament and to combat the proliferation of nuclear weapons

"For most Americans, there is an assumption that the nuclear threat receded with the end of the Cold War. Unfortunately, nothing could be further from the truth," said the May 12 letter from Bishop Oscar Cantu to Secretary of State John Kerry.

"In a multi-polar world where there are risks of nuclear proliferation and even nuclear terrorism, it is imperative that the world move systematically and relentlessly toward nuclear disarmament and the securing of nuclear materials."

Bishop Cantu, who heads the Las Cruces, N.M. diocese, wrote the Secretary of State in his role as chair of the U.S. bishops' Committee on International Justice and Peace.

"Please be assured of our prayers as you work for a world without nuclear weapons," the letter said.

The letter comes as the ninth review conference on the Treaty on the Non-Proliferation of Nuclear Weapons is underway at the United Nations in New York City until May 22. The bishops said it is "critically important" for the U.S. to help this conference succeed.

The United States and other countries that have nuclear weapons have a "particular responsibility for nuclear disarmament," it continued.

The bishops encouraged "bold and concrete commitments" to speed the process of "verifiable nuclear disarmament." This includes taking weapons off of "launch on warning" status to avoid a "catastrophic accident." The bishops urged deeper cuts in nuclear arsenals, ratification of a test ban treaty, and "serious negotiations" concerning fissile material.

The letter to Secretary Kerry cited the Holy See's statement at the beginning of the latest non-proliferation treaty conference.

Archbishop Bernadito Auza on April 30 told the treaty review conference that "ethics based on the threat of mutually assured destruction is not worthy of future generations."

"Lack of concrete and effective nuclear disarmament will lead sooner or later to real risks of nuclear proliferation," added the archbishop, who is the Holy See's permanent representative to the United Nations in New York.

The U.S. bishops said they share the view that any eroded credibility of the non-proliferation treaty could have "catastrophic consequences for all countries and for the future of humanity as a whole."