Force 17 is a security cadre responsible for protecting the Palestinian president and for providing security for visiting international delegations.
Former Palestinian leader Yasser Arafat regarded its members as some of his most trusted security personnel.
Members of Force 17 are given military-style training
They are the best-trained of the dozen or so overlapping security organisations operating under the Palestinian Authority's control.
Force 17 members wear military-style uniforms and are equipped with light weapons and armoured vehicles.
After several months of physical and arms training, they are routinely stationed away from their home towns and isolated from their families to assure undivided loyalty to the Palestinian leader.
The original force was founded in the mid-1970s in Lebanon by Ali Hassan Salameh - a legendary figure for Palestinians.
He was married to a Lebanese beauty queen who was crowned Miss Universe. She inspired a character in the John Le Carre novel The Little Drummer Girl.
Force 17 is said to have taken its name from Salameh's Beirut telephone extension.
The Israelis, who held him responsible for the attack on their athletes at the Munich Olympics in 1972, assassinated Salameh in 1979.
But the force he created survived and when Mr Arafat returned to Gaza in 1994, 300 Force 17 men accompanied him.
These veterans form the core of the militia, which since May 2006 has apparently been led by Mahmoud Damra.
The Israeli leadership has been highly critical of Force 17, saying its activities go beyond protection.
Mr Damra has been accused of co-ordinating attacks against Israel, which he denies. He escaped an Israeli assassination attempt in 2001.
Some Palestinian analysts have perceived Israel's targeting of Force 17 as an attempt to weaken or even dismantle the Palestinian Authority.