GAZA CITY, Gaza Strip — Israeli Prime Minister Benjamin Netanyahu said today that Israel must be ready for a “prolonged” military operation in the Gaza Strip and will “act aggressively and responsibly” until the mission is completed.

Israel launched the operation against Gaza’s Hamas rulers three weeks ago, initially from the air and then on the ground. Israel has said it wants to decimate Hamas’ ability to fire rockets at Israel and to destroy a network of Hamas military tunnels under the Gaza-Israel border.

However, Netanyahu indicated in a televised speech today that he is widening the objectives, saying that a demilitarization of Gaza must be part of any solution for the territory of 1.7 million people.

“There is no war more just than this,” Netanyahu said.

More than 1,000 Palestinians have been killed over the past three weeks, Palestinian health official say. According to the United Nations, about three-fourth of them were civilians. Israel has lost 43 soldiers and two civilians, as well as a Thai worker.

Netanyahu said Israel will “not end the operation without neutralizing the tunnels whose only purpose is” to kill civilians.

“We need to be ready for a prolonged campaign,” he said. “We will continue to act aggressively and responsibly until the mission is completed to protect our citizens, soldiers and children.”