The execution of another American hostage by the Islamic State terrorists is a tragedy for the family of Kayla Mueller, of Arizona. She died at the age of 26 after having gone to the Middle East to help the many good people of that region.

Her death is thus doubly a tragedy, for this country and for the people she sought to help.

We have no doubt that this latest outrage will help fuel a bipartisan response from the U.S. Congress.

After Mueller’s death was confirmed, President Barack Obama said those responsible will be brought to justice “no matter how long it takes.”

All should second that motion, but as the world knows — perhaps too well — politics still has a place in national security debates. We mourn the end of the tradition that politics should stop at the water’s edge, but if foreign affairs are contentious, we hope that Republicans and Democrats can unite around a strong commitment to doing what it takes, however long it takes.

Among the issues on Capitol Hill are debates about the precise wording of a new resolution authorizing a three-year deployment of force, although not ground troops, in the evolving battle against the Islamic State. The group has seized territory in Syria and Iraq, imposed a violent form of Sharia law and beheaded several hostages from the United States and other Western countries.

Last week, it distributed a horrifying videotape showing a Jordanian pilot being burned alive. That villainous action has had some positive results despite the loss of the pilot, Lt. Moaz al-Kasasbeh. Not only are the Jordanian people, but across the region other nations have contributed to the fight.

The United Arab Emirates again launched strikes from Jordanian bases against the Islamic State. The UAE had not been involved in strikes since December.

Needless to say, the United States and the various monarchies of the Persian Gulf, as well as Jordan, sometimes have significant differences of opinion.

Yet an ally is an ally, and the battle against a common enemy is an important bond.

Our friends in Jordan and in other parts of the Arab world share the revulsion at the barbarous cruelty demonstrated against not only Westerners but their own sons and daughters.

Our alliances in this case are not just a matter of a common enemy but a common ambition that violence and cruelty should not continue to haunt the Middle East.