The execution of six hostages in Gaza by Hamas last weekend complicated efforts to finalize a cease-fire agreement, but made its need even more urgent, US National Security Communications Adviser John Kirby told media earlier.

“We’re facing another massive failure here,” he said, adding that this “doesn’t mean we’re not going to keep trying.”

He focused, like other US officials in the previous hours, on the complications surrounding the exchange of up to 32 hostages for Palestinian prisoners in Israeli prisons.

“The prisoner swap has not been agreed upon and that’s really the heart of this deal,” Kirby said, explaining that Hamas not only killed hostages over the weekend but also changed some of the terms of the swap.

Kirby said talks were continuing by negotiators, but that no further joint meeting in one place, as had been held in previous weeks in Cairo and Doha, was planned.

“I cannot speak to the motive of the killing of these hostages, but we still believe that as tragic as it is, and it certainly is tragic, the ceasefire negotiations can and must continue,” he said.

At the same time, he spoke of, among other things, communication between the US and its counterparts in Qatar, Egypt and Israel, in order to make an effort to advance the procedures.