Though the abuse crisis is a global phenomenon, recent investigations in the United States have underscored the gravity of the scandal. A grand jury report in Pennsylvania last year found that 301 priests had sexually abused minors for some seven decades. Attorneys general in at least 16 other states have initiated investigations.

“The hurt caused by these sins and crimes has also deeply affected the communion of bishops, and generated not the sort of healthy and necessary disagreements and tensions found in any living body, but rather division and dispersion,” the pope wrote.

Only about 200 bishops are attending a retreat that the pope himself had insisted on, out of more than 450 active and retired bishops, according to a spokeswoman for the United States Conference of Catholic Bishops. A list of attendees has not been made public.

The pope said there was an urgent need “for a renewed and decisive approach to resolving conflicts.”

But the letter also suggested that the pope might not see eye-to-eye with the American bishops on policies they proposed last year, including a new code of conduct for bishops and a hotline run by a third party to report problems about bishops’ conduct.

“Loss of credibility calls for a specific approach, since it cannot be regained by issuing stern decrees or by simply creating new committees or improving flow charts, as if we were in charge of a department of human resources,” the pope wrote.

Francis met with United States bishops in September and suggested that they hold a meeting for spiritual reflection as a necessary step in responding to the “crisis of credibility.” He also asked the leaders of the American church to cancel their previously scheduled November meeting in Baltimore, and hold a spiritual retreat instead. But the bishops, aware of the anger in the pews, insisted on going through with the meeting so they could vote on a set of measures they had come up with to hold bishops accountable.