Jerusalem (CNN) -- Israeli authorities discovered and disarmed an explosive barrel Wednesday, the third to wash up on an Israeli beach this week, the Israel Defense Forces said.
The barrel was found Wednesday afternoon at Palmachim beach south of Tel Aviv.
On Monday, Islamic Jihad, the Fatah Al Aqsa Martyrs Brigade and the Nasser Salah A din Brigades issued a leaflet in Gaza claiming responsibility for sending three explosive devices to the coastal cities Ashkelon and Ashdod.
The other two barrels packed with explosives -- one found at Ashkelon and one at Ashdod -- were discovered Monday and disposed of.
In response, the IDF said, the Israeli Air Force attacked "two Hamas terrorist targets" in southern Gaza.
"One of the targets was a terror tunnel, used for the infiltration of terrorists into Israel, while the other was used for smuggling of weapons. Direct hits were identified," the IDF said.
Hamas, the movement controlling Gaza, has been vowing retaliation against Israel since one of the founding members of its military wing, Mahmoud al-Mabhouh, died last week in Dubai.
Al-Mabhouh's brother, Fayek al-Mabhouh, said that preliminary results of Hamas' investigation of the death showed his brother was killed by electrocution and strangulation with a piece of cloth.
Hamas officials accused Israel of assassinating Mahmoud al-Mabhouh. Israeli officials have not responded to that allegation.