VATICAN CITY — Pope Francis summoned the presidents of the world's bishops' conferences Wednesday to a summit on preventing clergy sex abuse and protecting children, responding to the greatest crisis of his papacy with the realization that Vatican inaction on the growing global scandal now threatens his legacy.

Francis' key cardinal advisers announced plans for the summit early next year the day before the pope meets with U.S. church leaders embroiled in their own credibility crisis from the latest accusations in the Catholic Church's decades-long sex abuse scandal.

The meeting, scheduled for Feb. 21-24, would assemble more than 100 churchmen to represent every bishops' conference. Its convening signals awareness at the highest levels of the Catholic Church that clergy sex abuse is a global problem, not restricted to some parts of the world or a few Western countries.

Victims' advocates immediately dismissed the event as belated damage control, an action publicized hastily as allegations regarding Francis' record of handling abuse cases — and accumulated outrage among rank-and-file Catholic faithful over covered-up crimes — jeopardize his papacy.

"There's absolutely no reason to think any good will come of such a meeting," given the church's decades of failure to reform, David Clohessy, former director of the victims' advocacy group SNAP, said.

"Criminal prosecutions, governmental investigations and journalistic exposes — stemming from brave victims and church whistleblowers — are the best way to protect kids, expose wrongdoers and end cover-ups," Clohessy said.

The summit was announced as Francis still works to recover from his botched handling of the sex abuse scandal in the Chilean church, sparked earlier this year when he repeatedly discredited victims of a notorious Chilean predator priest.

Francis eventually admitted to "grave errors in judgment" and took steps to make amends, including securing offers of resignation from every active member of Chile's bishops' conference.

Even as actions to address Chile were underway, Francis' papacy was jolted last month by accusations from a retired Vatican ambassador that Francis himself rehabilitated a top American cardinal accused of molesting and harassing adult seminarians.

The Vatican hasn't responded to Archbishop Carlo Maria Vigano's allegations against the pope and some two dozen other Vatican and U.S. officials, but has promised "clarifications" that could come after Francis' meeting Thursday with the U.S. delegation.

The U.S. delegation will be headed by Cardinal Daniel DiNardo, president of the U.S. Conference of Catholic Bishops, and includes Francis' top adviser on the clergy abuse issue, Cardinal Sean O'Malley.

DiNardo has said he wants Francis to authorize a full Vatican investigation of ex-Cardinal Theodore McCarrick, who was removed as cardinal in July following a credible accusation that he groped a teenager.

The Vatican has known since at least 2000 that McCarrick invited seminarians to his New Jersey beach house and into his bed, but was made a cardinal anyway.

DiNardo has also said Vigano's accusations deserve answers.

Amid such turmoil, a gathering of the global church leadership to discuss a specific problem — in the tradition of church synods and councils — is a good idea, but should take place sooner than February, said Christopher Bellitto, a church historian at Kean University in New Jersey.

Francis, he said, "has enormous amounts of what (German theologian) Hans Kung has called 'capital of credibility,' but he's losing it fast," Bellitto said. "This is an excellent action, but I think it should happen quicker than six months from now."

An open question in advance of the summit is whether the Vatican will issue a universal call for bishops and religious superiors to report suspected abuse to police; currently, it advises church leaders to report suspected abuse when it's required under local laws.

In 2011, as part of Pope Benedict XVI's attempts to take a tougher stand against sexual misconduct, the Vatican ordered the bishops' conferences to develop written guidelines on preventing abuse of minors and vulnerable adults. The guidelines were supposed to specify how bishops should tend to victims, punish offenders and keep pedophiles out of the priesthood.

While most conferences obliged, some have not. Vatican City itself has no such policy, even though the Holy See promised the United Nations five years ago it was developing a "safe environment program" to protect children inside the 110-acre (44-hectare) Vatican City State.

The U.S. Conference of Catholic Bishops issued a policy in 2002 that is regarded as the gold standard policy. It required accusations of abuse to be reported to police and the permanent removal from ministry of any priest found to have abused a minor.

But the U.S. plan has looked less like a model recently, given it exempted bishops like McCarrick. The McCarrick scandal and a Pennsylvania grand jury's allegations that some 300 priests had abused more than 1,000 children since the 1940s have left the credibility of U.S. church leaders in tatters. The grand jury. The report found that a string of bishops in six dioceses covered up for the predators, including the current archbishop of Washington, Cardinal Donald Wuerl.

The past of the Catholic Church is being dug up in other countries. German media reported Wednesday that a church-commissioned study detailed 3,677 abuse cases between 1946 and 2014. Every sixth case involved rape, more than half of the victims were 13-years-old or younger and at least 1,670 clergy were involved, Spiegel Online and Die Zeit said. The news outlets said the report was due to be released Sept. 25 and they obtained it in advance.

In their conclusions, the German researchers said there was evidence that some church files were manipulated or destroyed. Many cases were not brought to justice, and sometimes abuse suspects — primarily priests — were moved to other dioceses without new congregations being informed about the pastor's past, they said.