Leaders of the Roman Catholic Church in the United States opposed military action against Syria on Wednesday, saying it would led to "unintended negative consequences."
In a letter to President Barack Obama, the US Conference of Catholic Bishops said Washington should instead "work urgently and tirelessly" with others to end Syria's drawn-out civil war.
While condemning the use of chemical weapons in Syria, it said Pope Francis and Christian bishops in the Middle East have both urged the international community to avoid military intervention.
"They have made it clear that a military attack will be counterproductive, will exacerbate an already deadly situation and will have unintended negative consequences," it stated.
Co-signing the letter were New York's Cardinal Timothy Dolan, president of the Conference, and Bishop Richard Pates of Iowa, chair of its international justice and peace committee.
The Roman Catholic Church is the biggest Christian denomination in the United States.
Obama himself was in Sweden on Wednesday, en route to Russia for the G-20 summit where he is expected to rally global support for punitive strikes against Syria.
Pope Francis has declared this Saturday a day of fasting and prayer for Syria, having said last weekend that "God and history" will judge those who use chemical weapons.