Hamas has said its fighters in Gaza fired anti-tank missiles at Israel’s invading forces earlier today and Prime Minister Benjamin Netanyahu dismissed calls for a halt to fighting that has deepened the Palestinian enclave’s humanitarian crisis.

According to Reuters, the al-Qassam brigades, Hamas’ armed wing, said fighters clashed early on Tuesday with Israeli forces “invading the southern Gaza axis, (including) with machine guns, and targeted four vehicles with al-Yassin 105 missiles’, referring to locally produced anti-tank missiles.

The fighters also targeted two Israeli tanks and bulldozers in northwest Gaza with the missiles, al-Qassam said. Reuters was not able to confirm the reports of fighting. Israel’s military had no immediate comment.

Military specialists said Israeli forces are moving slowly in their ground offensive in part to keep open the possibility that Hamas fighters will negotiate the release of the hostages.

The relative caution with which Israeli troops have taken and secured slices of territory in the first days of sustained ground operations in Gaza stands in contrast to the past three weeks of unrelenting air strikes on the Mediterranean enclave, as well as to Israel’s previous land offensives there.