Washington (CNN) The mother of James Foley, an American journalist who was abducted in 2012 by ISIS and later brutally murdered, said Monday that she hopes the death of the terror group's leader this weekend will lead to its demise but warned the US to remain vigilant in its fight against terrorism.

"I'm hopeful that his demise will be a huge blow to the regrouping of ISIS. However, we need to continue to be very vigilant because they certainly want to regroup and bring back their reign of terror, but I'm very, very grateful," Diane Foley told CNN's Alisyn Camerota on "New Day."

On Sunday, President Donald Trump announced that ISIS leader Abu Bakr al-Baghdadi was dead after a US military raid in northwest Syria. Baghdadi had been at the helm of the organization that would later become ISIS since 2010, two years before James Foley was abducted by the group. For nearly two years after 2012, Foley's captors demanded millions in ransom payments and moved the freelance journalist between prisons before he was beheaded in a video that was widely publicized online.

Diane Foley, who serves as the president and founder of the James W. Foley Legacy Foundation, said on Monday that news of Baghdadi's death "came as such a welcome surprise" and that she was grateful to US troops involved in in the raid.

Foley also said she hopes the US military can locate American hostages held abroad and bring them back home.

Read More