Major military reinforcements arrived to the outskirts of El-Arish in Sinai Thursday morning coming from the Second Field Army Command in Ismailiya. The reinforcements sent to the border city with Israel include armoured vehicles, tanks and missile batteries in addition to hundreds of soldiers.

The reinforcements come as part of "Operation Eagle," launched in August 2011 and originally aimed at securing vital establishments in Sinai, and developed early Wednesday into combat engagements with militants after 16 border guards were killed Sunday in Rafah.

Sunday's assault by unidentified assailants laid bare the deteriorating security situation in Sinai. The newly deployed forces are expected to settle in the town of Shiekh Zuweid and the town of Rafah.

The reinforcements are considered the biggest since Egypt signed the 1979 Camp David Accords with Israel that left the Sinai Peninsula to a great extent demilitarised.

Since a security vacuum opened in Egypt with the fall of the security apparatus of the Mubarak regime on 28 January 2011, in the opening days of the Egyptian revolution, there has been a mutual understanding between Egypt and Israel concerning the necessity of raising the number of Egyptian soldiers in Sinai. The Egypt-Israel gas pipeline was sabotaged more than 10 times in less than a year, before the deal to sell gas to Israel was eventually abandoned. Egyptian police stations and checkpoints in Sinai have also been attacked by militants believed to be related to Jihadist Islamist groups.  

In August 2011, obtaining approval from the Israeli government, Egypt deployed 2,500 troops and 250 armored personnel carriers in Sinai. Yet after the Rafah attacks on Sunday, Cairo felt the necessity to send more.  

In a televised statement Wednesday afternoon, the Egyptian armed forces called on residents and Bedouin tribes in Sinai to help troops restore order and fulfill their security tasks.

Tensions in Egypt's North Sinai reached new heights in the early hours of Wednesday as Egyptian security forces engaged in battles with militants across several areas of the governorate, shortly after assailants opened fire on five joint military-police checkpoints.

Exchanges of fire continued until armored vehicles were sent to contain the situation and many of the gunmen were either killed or injured, eyewitnesses told Al-Ahram's Arabic language news website after the raids.

Military jets were also allegedly seen pounding several spots in the nearby town of Sheikh Zuweid as reports came in that Egyptian troops and helicopters were combing the eastern area of El-Halal Mountain, hunting down the armed insurgents.  

The Ministry of Interior confirmed Wednesday afternoon that Al-Risa, Mahager, El-Safa, El-Maasaia and El-Maghala checkpoints had been targeted by armed groups.