US National Security Advisor Jake Sullivan said on Sunday that it is Hamas, not Israel, that is obstructing a ceasefire agreement in Gaza.

Sullivan added on CBS that the United States will conduct an assessment of the extent of progress Israel has made towards improving the humanitarian situation in Gaza.

The administration of President Joe Biden told Israel in a letter dated October 13, signed by Secretary of State Antony Blinken and Secretary of Defense Lloyd Austin, that it must take steps within 30 days on a series of measures, or risk restrictions on US military aid to it.

Sullivan told CBS' "Face the Nation": "We'll make our judgments this week on what kind of progress they've made. And then Secretary Austin and Blinken and the president will make judgments on what we do in response, and I won't preempt The command".

The US deadline is set to expire just days after global food security experts said there was a "strong possibility that famine is imminent in areas" of northern Gaza as Israel continues its military attack on Hamas members there.

Israel began its massive military attack in northern Gaza last month. The United States said it was monitoring the situation to ensure that Israel's actions on the ground show that Prime Minister Benjamin Netanyahu's government does not have a "starvation policy" in the north.