Secretary of Defense Ash Carter said in a speech Monday that the Orlando terrorist attack demonstrated the urgency of defeating the Islamic State terrorist organization, drawing a clearer connection between radical Islamic terror and the massacre than others in the Obama administration.

The killer of 49 people at a gay nightclub pledged allegiance to ISIS in calls with negotiators and described himself as a soldier of the caliphate. However, published transcripts of his conversations with negotiators omitted references to Islamic terror. Attorney General Loretta Lynch claimed such measures were done so as not to "further his propaganda."

In a keynote address at the Center for a New American Security's national security conference, Carter described five immediate challenges facing U.S. national security: the prospect of Russian aggression, Chinese aggression in the Pacific region, North Korea's nuclear provocations, Iranian malign influence in the Gulf, and the threat of terrorism, in particular "accelerating the defeat of ISIL."

Obama administration members use the acronym ISIL instead of the more common ISIS.

"Last week's tragic shooting in Orlando underscores the urgency of that last one," Carter said. "It reminds that ISIL not only tyrannizes the population where it rose in Syria and Iraq, but it also wants to spread its evil ideology and to plot or inspire attacks on Americans, including here at home. And Orlando further steels our resolve to carry out all the aspects of our coalition military campaign plan.

"First, destroying ISIL's parent tumor in Iraq and Syria, which is necessary. Not sufficient, because second, we need to combat ISIL's metastasis worldwide, wherever it appears, and third, help protect the homeland and our people."

Later in the address, Carter said the Orlando killings served as another reason why the global coalition needed to deliver the terror organization a "lasting defeat."

"Orlando is a reminder that all nations must do more to defeat ISIL," he said. "The sooner we deliver it a lasting defeat, the safer we'll make our homelands and our people."

Note (3:48 p.m.): This article has been updated with further remarks by Carter.