STRASBOURG, France — Pope Francis said that while the self-declared Islamic State in Iraq and other extremist groups represent a real threat, so, too, does “state terrorism” that he said breeds “anarchy of another level.”

In remarks to reporters on the papal airplane at the end of a daylong trip to Strasbourg, Francis did not single out any specific state as guilty of terrorism. However, his comments clearly marked a note of caution about unilateral military strikes against ISIS and other terrorist groups, whether led by the United States or any other nation.

In the same breath, Francis also addressed a burgeoning Catholic sexual abuse scandal in Spain involving at least 10 priests, saying “the truth is the truth, and we must not hide it.”

The comments on Tuesday came after the pope gave speeches to both the European Parliament and the Council of Europe.

The pontiff defined state terrorism as when “every state feels the right to massacre terrorists.”

When a state launches an indiscriminate response, Francis said, “many innocents also fall.” He said that “no state has the right on its own to stop an unjust aggressor” in the absence of an “international consensus.”

Those comments seemed calculated to reframe an earlier response from the pontiff last August about US-led airstrikes against the Islamic State, at the end of his trip to South Korea. Francis said then “it is legitimate to stop an unjust aggressor,” which was taken as a limited papal endorsement of the US action.

Although Francis did not single out any specific nation as guilty of state terrorism, the charge is one that Palestinians have long directed at Israeli security policies, and others have applied to American military interventions in various parts of the world.

The pontiff also insisted that although dialogue with the self-proclaimed Islamic State currently menacing much of the Middle East seems “almost impossible,” for his part, “the door is always open.”

On another front, Francis also said that he received recent criminal charges against several Catholic priests in Spain — charges that he himself was involved in triggering — with “great pain,” but that “the truth is the truth, and we must not hide it.”

In Spanish media accounts, Francis has been credited with playing a role in exposing a criminal pedophile network in Granada, Spain, that involves at least 10 priests.

In August, one of the alleged victims, now a college professor identified only as “Daniel,” reportedly wrote to Francis in August to describe his abuse and to seek counsel. Francis encouraged the victim to come forward. That led to both a police investigation and Church disciplinary procedures against the accused priests.

Francis confirmed that version of events on Tuesday.

“I received it and I read it,” Pope Francis said of the victim’s letter. “I called the person and said, ‘Tomorrow, go to your bishop.’ I wrote to the bishop so he could start his work, do the investigation, and go ahead,” the pope said.

Pope Francis’ record on the abuse scandals has recently drawn mixed reviews.

On one hand, a new anti-abuse commission created by the pope is moving forward with a variety of projects, and Francis also launched an investigation of Bishop Robert Finn of Kansas City-St. Joseph, to date the lone American bishop criminally convicted of a misdemeanor count of failure to report a charge of child abuse.

On the other, The Boston Globe reported this week that the pope’s nominee as the Promoter of Justice in the Vatican’s doctrinal department, in effect its top prosecutor on abuse issues, was one of several Jesuit officials more than a decade ago who allowed a notorious abuser to remain in ministry.

In the wake of strong papal rhetoric on Tuesday at the European Parliament and the Council of Europe, including strong pleas for immigrants, the unemployed, and the environment, as well as his criticism of a “cult of opulence which has become unsustainable,” Francis was asked if he is a “Social Democratic Pope.”

In European politics, the Social Democrats tend to be the main center-left formation, often the rough equivalent of American Democrats.

Laughingly, the pontiff described the question as “reductionistic.”

Francis said he doesn’t want to represent any political faction, but rather wants to present “the message of the Gospel” and “the social teaching of the Church.”

The pope limited the scope of his exchange with reporters Tuesday to the content of his trip to Strasbourg, as opposed to the free-wheeling press conferences he’s held at the end of longer overseas journeys.

Pope Francis also said that although no visit to France is currently on the books, he does plan to make one at some point. Aside from Paris and the healing shrine of Lourdes, he said, he’s asked to go to “some city that’s never had a pope come to them.”

On the issue of human trafficking, which has emerged as a key social concern for Francis, he said that “slavery is a reality that’s inserted into social reality today,” and that “we must not close our eyes to it.”