Israel’s military said it is undertaking an operation at a major Gaza hospital it accuses Hamas of using as a command center, a move that could intensify international criticism of the country.

Israel Defense Forces are “carrying out a precise and targeted operation against Hamas in a specified area in the Shifa Hospital,” the IDF said in a statement early Wednesday. The military earlier “conveyed to the relevant authorities in Gaza once again that all military activities within the hospital must cease within 12 hours. Unfortunately, it did not,” according to the statement.

The scale of Israel’s move wasn’t immediately clear. The IDF said its forces included medical teams and Arabic speakers. An official at the Hamas-run Gaza health ministry said tanks were at the front gate.

The IDF operation was widely expected after Israel said the hospital and tunnels underneath were utilized by Hamas to hide forces following the group’s Oct. 7 attack on Israel. Hamas — which is a designated terrorist organization by the US and European Union — denies Israeli accusations that it uses hospitals as bases.

The Shifa hospital in recent days had become the center of international attention on the conflict in Gaza, with Israel and Hamas trading accusations over the facility.

Concerned about rising civilian casualties in the conflict, US President Joe Biden this week called on Israel to take “less intrusive action” at the Shifa hospital.