In March 2007, a car carrying over 100 kilograms of explosives succeeded in infiltrating downtown Tel Aviv from the West Bank town of Kalkilya. The terrorists' plan was to detonate the car on Seder night. The existence of this cell, which was the target of the Palestinian clashes in Kalkilya on Sunday, had been the IDF's excuse for refusing to scale back its operations in the West Bank city and implement there and in Tulkarm what is being called the "Jenin model." Under the Jenin model, the IDF has scaled back operations in that city, removed checkpoints in the area, permitted the deployment of US-trained Palestinian forces and allowed Israeli Arabs into the city to boost the local economy. In addition, Israel and the PA are working on the construction of an industrial zone. Following the Palestinian Authority's operation in Kalkilya on Sunday - during which six Palestinians were killed, including the two most-senior Hamas operatives in the city, the Civil Administration in Judea and Samaria coordinated the evacuation of one of the wounded PA policemen to an Israeli hospital. Sunday's operation - the deadliest outbreak of violence since the PA began a crackdown on Hamas two years ago - came just days after Mahmoud Abbas met with President Barack Obama in Washington, where he accused Prime Minister Binyamin Netanyahu of being an obstacle to peace. The operation in Kalkilya is meant to reinforce that message. On the one hand, it shows the US that Abbas is serious about cracking down on Hamas. On the other hand, it is meant to pressure Israel to relinquish its control over Kalkilya to the PA. Israel recognizes the effectiveness of the US-trained forces that operate in the West Bank. During Operation Cast Lead in the Gaza Strip, senior officers confirmed that the PA forces were responsible for keeping a lid on terror in the area and preventing Hamas from launching attacks inside Israel. But while the officers were willing to recognize the PA competence, they did express concern regarding the possibility that the IDF would be asked to withdraw its forces from various West Bank cities and transfer responsibility to the Palestinian forces. "The key to our success is our operational freedom in the West Bank," explained a source in the Central Command. "That is what is keeping terror down to a minimum." These two considerations - on the one hand bolstering the PA by transferring security control in the cities and on the other hand maintaining IDF operational freedom - appear contradictory. It will be up to Netanyahu and Defense Minister Ehud Barak to create the required balance while at the same time appeasing the Obama administration and ensuring Israeli security.