President-elect Donald Trump is demanding the immediate release of Israeli hostages still being held in Gaza, saying that if they are not freed before he is sworn into office for a second term there will be “HELL TO PAY."

“Please let this TRUTH serve to represent that if the hostages are not released prior to January 20, 2025, the date that I proudly assume Office as President of the United States, there will be ALL HELL TO PAY in the Middle East, and for those in charge who perpetrated these atrocities against Humanity," Trump wrote in a post on his Truth Social site.

He added that, "Those responsible will be hit harder than anybody has been hit in the long and storied History of the United States of America. RELEASE THE HOSTAGES NOW!”

It was not immediately clear whether Trump was threatening to directly involve the U.S. military in Israel’s ongoing campaign against Hamas in Gaza. Trump allies have said he hopes there will be a ceasefire and hostage release deal before he returns to office early next year.

Israeli Prime Minister Benjamin Netanyahu’s office declined comment. But the country's president, Isaac Herzog, welcomed Trump's comments in a social media post.

"Thank you and bless you Mr. President-elect @realDonaldTrump," he wrote on X. "We all pray for the moment we see our sisters and brothers back home!"

The war in Gaza began when Hamas-led militants stormed into southern Israel, killing some 1,200 people, mostly civilians, and taking around 250 people hostage on Oct. 7, 2023. Some 100 are still held inside Gaza, around two-thirds believed to be alive.

Trump’s threat came hours after the Israeli government confirmed the death of Omer Neutra, a dual US--Israeli citizen, whose body is still believed to be held by Hamas in Gaza, according to the Israeli government.

Days earlier, Hamas released a hostage video of Edan Alexander, who was serving in the Israeli military when he was taken by Hamas to Gaza. Filmed under apparent duress, Alexander calls on Trump to work to negotiate for his freedom and that of the remaining Hamas hostages.

The Biden administration is mounting a last-ditch effort to try to restart talks between Israel and Hamas now that it has brokered a fragile ceasefire between Israel and Hezbollah in Lebanon. But the administration has said that Hamas has yet to show a willingness to reengage in negotiations and that the group isn’t concerned for its own lives or the lives of Gaza civilians.

Israel’s retaliatory offensive for the attack has left at least 44,429 Palestinians dead, according to Gaza’s Health Ministry. The war has destroyed vast areas of the coastal enclave and displaced 90% of its population of 2.3 million people — often multiple times.