US intelligence agencies assessed that Hamas and another Palestinian group fighting Israel used al-Shifa Hospital in Gaza to command forces and hold some hostages but largely evacuated the complex days before Israeli troops entered it, according to a US official.
The official, who spoke on condition of anonymity, told Reuters that both Hamas and Palestinian Islamic Jihad used the complex to command forces fighting against Israel.
US intelligence agencies have not disclosed the evidence on which they based their assessment.
The official said the US had independently confirmed the information.
Israel also said that the al-Shifa, which it occupied earlier in the war in Gaza, was being used by Hamas. Israeli forces entered the hospital in November.
The targeting of the hospital raised global concern about the fate of the civilians and patients who were inside it.
Last month, the World Health Organization (WHO) described the emergency department of the main health facility in the Strip as resembling a "bloodbath."
The US government believed that Hamas used the hospital complex and the sites underneath it to carry out command and control activities, store some weapons, and take a small number of hostages.
According to the official, the US intelligence services obtained information that Hamas fighters had largely evacuated the complex days before the Israeli operation and destroyed documents and electronics as they left.
The New York Times (NYT) first reported the US intelligence assessment. A classified version of the assessment was sent to lawmakers in the US Congress.
In mid-November, Israeli tanks advanced toward al-Shifa while some patients were still inside.
Israel said that the hospital is located above tunnels containing headquarters for Hamas fighters who use patients as shields, which Hamas denied.
The NYT reported that the Israeli assessment was at least partially correct, that some hostages were being held in or under the compound, but they appeared to have been moved as Hamas evacuated.
In November, White House National Security spokesman John Kirby said Hamas fighters were taking shelter at the hospital and using the facility as a shield against military action, putting patients and medical staff at risk.
"We have our intelligence that convinces us that Hamas was using Al Shifa as a command-and-control node, and most likely as well as a storage facility," Kirby said in November. Washington had, at the time, not declassified the sources of the US intelligence.
The courtyard of al-Shifa Hospital turned into a cemetery containing dozens of mass graves of victims killed during Israeli bombing.