Israeli troops have massed on the Gaza border, preparing for a possible strike. A major incursion is planned if the Palestinian authorities do not return an Israeli soldier abducted during an attack by militants on a border post at the weekend.During the raid – carried out by fighters from the armed wing of the ruling Hamas party and other factions – two other soldiers were killed. A deadline has been given to the Palestinians to release Corporal Gilad Shalit, a 19-year-old conscript. It is believed he may have been wounded in Sunday’s attack. The incident has put pressure on Prime Minister Ehud Olmert and given ammunition to critics who say his plan for a unilateral withdrawal from parts of the West Bank would bring “Palestinian terror” closer to Israel’s doorstep. Olmert has talked tough, declaring: “We will reach everyone, no matter where they are. There will be no immunity for anyone.” A senior aide to the Palestinian president said he hoped the soldier would be found promptly. Otherwise, he said, “the border crossing will remain closed and the incursions will start and the assassinations will continue”.