Israeli forces killed at least 18 Palestinians on the second day of a stepped-up military offensive in the Gaza Strip on Tuesday that Islamist militant group Hamas said was jeopardizing ceasefire talks. Qatari and Egyptian mediators, backed by the United States, have accelerated their efforts this week to seal a ceasefire deal aimed at ending the Gaza war and releasing Israeli hostages in Gaza in return for Palestinians prisoners jailed in Israel. On Tuesday, Israeli tanks deepened their incursion into some Gaza City districts such as Shejaia, Sabra and Tel…