Israel said Wednesday it was behind a car bomb outside western Gaza City's police headquarters that killed a senior Palestinian militant, who it said was planning an attack against Israeli and United States targets in the Sinai peninsula, DPA reported.
Lieutenant Colonel Avital Leibovich told reporters that Mohamed al-Nemnem, 27, was a "ticking bomb."
The Israel Defence Forces and the Shin Bet internal security organization thus jointly carried out the targeted killing on Wednesday as they had a "window of opportunity" to do so, she said.
Al-Nemnem was reportedly a member of the radical Army of Islam militant group, which kidnapped British reporter Alan Johnston in March 2007 and released him four months later.
Palestinian witnesses and security officials said the explosion in the car was caused by a bomb planted under the driver's seat.
The Hamas-run Interior Ministry, however, had said in an earlier statement that it believed the explosion to have been caused by a missile fired by an Israeli drone.
Leibovich said she could not give details, saying "I don't want to tell you exactly how this happened, but he was targeted with a bomb."
According to an earlier army statement, the Sinai attack was being planned in cooperation with Hamas members in the Gaza Strip. It also alleged that the Army of Islam has links with al-Qaeda and identified with the cause of "global jihad."
"This Mohamed al-Nemnem had a very direct involvement in planning terrorist attacks against both American and Israeli targets in the Sinai," Leibovich said.
The targets were to be Israel Defence Force soldiers, Israeli residents and Americans, she said.
She could give no further information on the attack she said was being planned, saying only: "Look, it's in the Sinai, so there are limited possibilities here."
"It did not happen because we took this guy down," she added.
Leibovich said the targeted killing would not necessarily mean an end to an unwritten truce that Israel and Hamas, the radical Islamist movement ruling Gaza, have largely adhered to - despite on-and-off rocket and mortar attacks, and Israeli retaliatory airstrikes - since the three-week Gaza war of the winter of 2008-2009.
But Israel could carry out more such assassinations in the event it had information of more "ticking bombs," she noted.
She also said the Egyptians were not involved in the targeted bomb attack, but hinted that Washington was given advance notification.
"Without getting specifically into more details, I can tell you there is very good cooperation between us and the Americans," she said.
"We have an ongoing relationship with the Americans, as well as with other forces, and from time to time we pass on information as with other sources," she said.
The last targeted killing of a Palestinian militant was on October 7, when Israel assassinated a member of the armed wing of the radical Popular Front for the Liberation of Palestine movement whom it also described as a "ticking bomb."
Although the Army of Islam collaborated with Hamas in a June 2006 cross-border raid that saw Israeli corporal Gilad Shalit kidnapped, there have also been tensions - sometimes violent - between the two groups.
Al-Nemnem had in the past been arrested by Hamas security forces.