- Associated Press - Monday, August 6, 2012

EL-ARISH, EgyptEgypt's military vowed on Monday to hunt down those behind the killing of its 16 soldiers at a checkpoint along the Sinai border with Israel.

It called the attackers “enemies of the nation” and suggested they were Egyptian Sinai-based militants who received Palestinian support from the Gaza Strip.

The attackers’ attempt to break through the border after killing the soldiers could increase tensions with Israel, which has stepped up pressure on Egypt to clamp down on the lawless border region.

The “group that staged yesterday’s attack is considered by the armed forces as enemies of the nation who must be dealt with by force,” the military said in a written statement.

The attack and the army’s promised crackdown add to the host of political, economic and security crises that festered under ousted President Hosni Mubarak and that now face his successor, newly elected President Mohammed Morsi, whose powers are limited by the military.

It could mark an escalation in the Sinai’s decade-long low-level Islamist insurgency. Sunday’s attack is among the worst against Egyptian soldiers.

Israel said its aircraft killed between six and eight terrorists. Egyptian officials have said six attackers were killed. A statement by the Egyptian armed forces said 35 militants took part in the attack, suggesting that close to 30 attackers may be on the run.

Security and military officials said at least two helicopter gunships arrived in the border town of El-Arish on Monday to join the hunt for the militants believed responsible. Israel meanwhile stepped up pressure on Egypt to clamp down on the lawless border region.

In the first direct indication that the attackers may have had the help of Palestinian militants, the military’s statement said “elements from the Gaza Strip” aided the attackers by shelling the Egyptian-Israeli border crossing of Karam Abu Salem with mortars as the attack was taking place.

The security and military officials said counterterrorism units arrived in the border town of El-Arish on Monday and joint police-army patrols were combing the ground. Aircraft patrolled the sky overhead, they said.

The officials said more helicopter gunships were expected to join the two already in the border zone.

The Sinai has seen a surge of violence since Mubarak’s ouster last year, but Sunday’s attack was the worst in several years. Suspected Islamists attacked the checkpoint in the border town of Rafah at sunset, killing the soldiers as they were sitting down for the traditional meal breaking the fast in the holy month of Ramadan.

The attackers then commandeered two of their vehicles and burst through a security fence into Israel, according to Israeli officials. They said the incursion was quickly spotted and hit with an airstrike. Egypt's military said only one armored vehicle was commandeered.

In Israel, Prime Minister Benjamin Netanyahu on Monday paid an unannounced visit to the site where the militants broke through, praising Israeli security forces for their swift response and expressing regret for the loss of the Egyptian lives.