Defense secretary offers more details on military raid in Syria, al-Baghdadi's death
Esper has been Secretary of Defense since July.
Calling it a "bold decision," the defense secretary offered more details on the mission that led to the death of Islamic State leader Abu Bakr al-Baghdadi on ABC's "This Week" Sunday.
"This is a great day for America, it's a great day for the world," Defense Secretary Mark Esper said. "The president made a bold decision to launch this raid and our military service members and our interagency partners executed brilliantly."
"[Al-Baghdadi was] a thug, a murderer and the world is better off without him," he added later.
President Donald Trump announced the death of the ISIS leader in an address to the nation Sunday morning. Al-Baghdadi was targeted Saturday in a nighttime raid by U.S. special operations forces in Syria.
The president said al-Baghdadi, "went into a dead-end tunnel, whimpering and crying and screaming all the way," and died when he detonated a suicide vest.
"[Baghdadi] spent his last moments in utter fear, in total panic and dread, terrified of the American forces bearing down on him," Trump said.
The U.S. took sensitive material and information from the compound, including information on the Islamic States' origins and future plans, Trump said, adding that no U.S. personnel were lost in the raid.
Esper, who watched the raid from the situation room with the president, said on "This Week" that special operations forces found al-Baghdadi due to good intelligence work and cooperation from partners.
"The stars started lining up some time ago," he said, adding that special operations forces started rehearsing in the last couple weeks. "It wasn't until Thursday and then Friday the president chose his option and gave us the green light to proceed."
Esper said that special operations forces came in by helicopter and were on the ground for more than two hours, with less than 100 U.S. forces deployed in the raid.
The secretary of defense also confirmed that two of al-Baghdadi's wives were killed in the raid, in addition to the three children killed that Trump described.
Esper also responded to a statement on the raid from Diane Foley, the mother of freelance journalist James Foley who was executed by an ISIS militant in 2014.
"She's right, I think all the praise goes to our service members and our intelligence professionals and others who took this on," he said. "And the message is, if you're a leader in ISIS, if you're a leader in a terrorist group we are going to come after you and we will hunt you relentlessly."
Al-Baghdadi was last seen alive in a video in April, in which he discussed the loss of an ISIS stronghold and praised attacks in Sri Lanka that killed more than 250 people.
Esper would not comment on the location of al-Baghdadi's body following the operation.
The U.S. had been considering a plan to leave some troops in eastern Syria to protect oil fields following a conflict between Turkey and Kurdish forces.
Esper confirmed that the U.S. would use some mechanized forces to protect oil fields.
"We are now taking some actions, I'm not going to get into the details, to strengthen our position in Dayr az Zawr to ensure that we can deny ISIS access to the oil fields," he said at a press conference in Brussels on Friday.
ABC News' Martha Raddatz, Luis Martinez, John Santucci, James Gordon Meek, Elizabeth McLaughlin and Justin Doom have contributed to this report.