BRAINTREE -- Massachusetts' Catholic bishops are joining the U.S. Conference of Catholic Bishops and other ordinaries from around the country in urging senators to ratify the Strategic Arms Reduction Treaty, know as START, being brokered by the United States and Russia.

Cardinal Seán P. O'Malley and the bishops of the other three dioceses in Massachusetts jointly signed a letter to Sens. John Kerry (D) and Scott Brown (R) urging them to ratify the new START. The letter was dated Nov. 15 and transmitted through the Massachusetts Catholic Conference, the public policy arm of the bishops in the state.

The letter affirmed the Catholic Church's longstanding support of nuclear disarmament and non-proliferation, which the state's bishops say is rooted in the Church's commitment to the dignity of human life.

"The bishops felt it was something important for us to do," said Massachusetts Catholic Conference Executive Director Gerry D'Avolio. "We have always supported peace efforts, particularly with nuclear proliferation."

D'Avolio explained the timing of submitting the letter, saying the Senate could move to approve the treaty in its current lame duck session, though they could push discussions on the treaty until after January, when the new Senate takes their seats. The Senate must ratify all treaties by a two-thirds vote.

The version of the START pact currently under discussion would revise the former START agreement that was signed 18 years ago, as the Cold War was ending.

The treaty expired last December, and a new version was signed in Prague April by President Barack Obama and Russian President Dmitry Medvedev after a year of negotiations.

The new agreement would not only commit the United States and Russia to cuts in their long-range, ready-to-use weapons but would also extend a 15-year system allowing each country to check the other's nuclear facilities. It calls for both countries to reduce their strategic arsenals -- weapons deployed on long-range missiles, bombers and submarines -- to 1,550 each. Under the previous START pact, both countries reduced their strategic arsenals to 2,200 weapons each.

Once the treaty is ratified, both countries will have seven years to reach the agreement's targets.

In mid-September the Senate Foreign Relations Committee, which is chaired by Kerry, voted 14-4 in favor of the START pact.

The agreement has the support of current and former administration officials and military leaders, although some Republican senators have questions about the treaty.

The Associated Press reported Nov. 16 that Brown is still evaluating the treaty, and quotes a Brown spokeswoman as saying the senator believes the treaty fails to provide for the modernization of the country's existing weapons and assure it will not affect missile defense. Kerry, meanwhile, supports the pact.

Catholic News Service and Associated Press materials contributed to this report.