Hamas' wants the Israel-imposed blockade in Gaza lifted and their prisoners released before they will consider agreeing to a lasting ceasefire.
"Unless the conditions of the resistance are met, the negotiating team will withdraw from Cairo and then it will be up to the resistance in the field," a senior commander of the armed wing told Reuters.
So far Israel has resisted the demands but Israel's armed forces chief, Lieutenant-General Benny Gantz said should Hamas disrupt the calm "we will not hesitate to continue to use our force wherever necessary to ensure the security of Israeli citizens near and far."
Mark Regev, a spokesman for Israel Prime Minister Benjamin Netanyahu, told Reuters television: "For Israel the most important issue is the issue of demilitarisation. We must prevent Hamas from rearming, we must demilitarise the Gaza Strip,"
There have been two days of quiet in Gaza. No rockets or missiles, no more destroyed houses, no more ambulance sirens screaming.
A three-year-old girl has been rescued from Gaza and brought to London for life-saving heart surgery.
A small team of NHS doctors and surgeons is travel to Gaza to set up facilities and establish how best to use specialists and equipment.