Israel has reduced its number of air raids on the Gaza Strip while increasing its ground offensive by deploying reserve units.It is the first time reserve units are used in the conflict since it started just over two weeks ago. On Sunday, Israeli warplanes focussed their attacks on the 15-kilometre long border between Gaza and Egypt, dropping penetration bombs aimed at destroying the tunnels Hamas is accused of using to smuggle weapons into Gaza. The ground troops have now started pushing into heavily populated areas of Gaza City, where fierce fighting was reported on Sunday. Any information is difficult to verify as Israel is preventing foreign journalists from entering into the Strip. It’s estimated up to 900 Palestinians have been killed since the start of the conflict on December 27, including 40 on Sunday alone. The number of Israelis killed stands at 13, including three civilians.