This could include the two terrorists who carried out the Sarona Market attack which killed four people and injured 16 in Tel Aviv on Wednesday evening. They easily crossed from the West Bank and then were brought north to Tel Aviv.
The Israelis murdered in Tel Aviv Sarona Market terror attack were: Ido Ben-Ari, 42, from Ramat Gan; Ilana Nave, 39, from Tel Aviv; Dr. Michael Feige, 58 from Ramat Gan; and Mila Mishayev, 32, from Rishon Lezion.
It's possible to count on one hand the number of attackers who had permits to work legally in Israel.
The security forces' assumption is that if a Palestinian is unemployed, there is a much higher likelihood that they will become terrorists. As part of this security worldview, Israel has raised the number of Palestinian work permits by 30,000 overall, to 120,000 Palestinians from the West Bank, are making their livings in Israel.
It still hasn't been announced if the two terrorists ever had an entry permit into Israel, and the security forces are checking to see if either of them were ever stopped due to security issues.
Mohammad and Khaled Mahamrah lived in the city of Yata in the southern West Bank. Dozens of terrorists have come from this area and illegally infiltrated Israel for the purpose of carrying out terror attacks over the past few years, including a bus bombing in Bat Yam in 2013.
Meanwhile, the security barrier still hasn't been completely constructed around the West Bank, enabling thousands of illegal workers, and some terrorists, to cross from the West Bank to the Israeli heart land with east. Areas where the barrier has yet to be completed include the Hebron region, where the barrier was planned to pass within a few kilometers of the terrorists' house.