The U.S. Conference of Catholic Bishops joined about four dozen other national organizations in amassing more than 50,000 signatures on a petition asking for a change in the United States' "outdated" nuclear arms policy.
"You must act now to reduce the nuclear danger and the role of nuclear weapons," said the petition, addressed to President Barack Obama.
The petition urges Obama to "end outdated U.S. nuclear war-fighting strategy, dramatically reduce the number of U.S. nuclear weapons and the number of submarines, missiles and bombers that carry those weapons, and take U.S. nuclear weapons off high alert.
Maintaining large numbers of nuclear forces on alert increases the risk of accident or miscalculation."
The United States possesses about 1,700 strategically positioned nuclear warheads. Russia has about 1,500.