The IDF has begun actively calling up the 40,000 reserves approved to it by the cabinet for Operation Protective Edge.
IDF chief of Staff Lt.-Gen. Benny Gantz requested the call-up of 40,000 reserves in order to replace conscripted forces in the West Bank, and enable their deployment to the Gaza border.
The cabinet approved the request and the IDF has already begun issuing reserve notices.
The IDF had previously called up 1,500 reserves on Monday.
Operation Protective Edge, which has seen the IAF strike some 100 terror targets in the Gaza Strip, came after more than 250 rockets were fired into southern Israel in recent weeks.
The rocket fire continued on Tuesday, with dozens of rockets fired into Israel, including some which targeted Beersheba and Ashdod.
Following high level security deliberations Tuesday morning Prime Minister Binyamin Netanyahu decided to expand the military operation in Gaza, including beginning preparations for a ground operation.
No time limit was put on the operation but senior diplomatic officials said it could be "for a long time."
The objective of the operation, according to the officials, is to return quiet to the South, but the equation that "quiet would be met with quiet" was no longer the operative principle.
During the day Netanyahu expected to talk to a number of world leaders to explain Israel's position and another security cabinet meeting will be held later in the afternoon if necessary.