Yet Abbas seems to be facing an even bigger challenge. The events of the past few days have shown that many of the militiamen belonging to his ruling Fatah party are operating openly together with Islamic Jihad in the West Bank and Gaza Strip.
Islamic Jihad operative Luai Sa'di, who was killed in an IDF operation in Tulkarm earlier this week, had been working closely with Fatah gunmen in the area.
Sa'di's cohort, Majed al-Ashkar, a senior leader of Fatah's armed wing, the Aksa Martyrs Brigades, was also killed in the IDF raid. Sources in Tulkarm said the two men had formed a joint Fatah-Islamic Jihad cell responsible for a series of attacks on Israel over the past 18 months.
Similar cells have also begun operating in Jenin and Nablus, where Fatah and Islamic Jihad members are often seen roaming the streets together. And in yet another indication of the harmony between the two groups, masked gunmen belonging to Fatah and Islamic Jihad held a joint press conference in Gaza City Wednesday night to claim responsibility for the Hadera attack.
The fact that such a press conference is held in public in the center of Gaza City - and is attended by scores of journalists - shows that the PA security forces have almost no control over what's happening in the area.
The phenomenon poses a serious challenge to Abbas, who is in the process of incorporating hundreds of disgruntled Fatah gunmen into the PA security forces. It could also jeopardize the PA's efforts to establish five military training camps in the West Bank for the Fatah gunmen.
The growing cooperation between Fatah and Islamic Jihad activists in the West Bank has prompted some of Abbas's top aides to voice concern that Islamic Jihad elements would now try to infiltrate the PA security forces.
According to one aide, dozens of Fatah gunmen have "defected" to Islamic Jihad in protest against the PA's failure to pay them salaries and give them high ranks in the security forces.
"It's not a matter of ideology, but money," he explained. "And the money is coming from Damascus and Hizbullah."