December 14 | Top Biden adviser Jake Sullivan travels to Israel as Gaza refugees press Egyptian border

Hamas leader Yahya Sinwar’s days appeared to be “numbered,” a senior U.S. officials said Thursday.

“I think it’s safe to say his days are numbered. I also think it’s safe to say it doesn’t matter how long that takes,” the official said, according to Reuters.

“I also think it’s safe to say it doesn’t matter how long it takes…justice will be served,” the senior administration official added, noting that Sinwar has “American blood on his hands,” the Times of Israel reported.

Israel has accused Sinwar of being the mastermind behind the terror group’s Oct. 7th attack that killed some 1,200 people resulted in around 240 people being held captive. Leaflets were recently dropped into the Gaza Strip offering cash rewards amounting to $1 million for information leading to the capture of Hamas’ top leaders.

A $400,000 reward is being offered for Sinwar.

Israeli forces have been working to track Sinwar and his cohorts for weeks. They surrounded his home in southern Gaza earlier in December, but he is believed to have taken shelter somewhere in the labyrinth of Hamas tunnels beneath Khan Younis, the largest city in southern Gaza.

Sinwar is known in Israel as the “Butcher of Khan Younis” for his violent and cruel torture methods against his enemies, both Israeli and Palestinian.

Sinwar is a longtime militant activist and joined Hamas shortly after its founding in 1987. Two years later, he was arrested by Israel for his involvement in the abduction and killing of two Israelis, as well as the torturing and murder of four Palestinians he considered to be collaborators.

Sentenced to life in prison, Sinwar ended up serving 22 years in an Israeli jail and was eventually released as part of a prisoner exchange for the abducted Israeli soldier Gilad Shalit in 2011.

Fox News Digital’s Chris Pandolfo and Ruth Marks Eglash contributed to this report.