Egypt has declared a state of emergency in the northern and central parts of Sinai following gun and bomb attacks which killed 31 soldiers.
At least 30 others were injured in the coordinated bomb attacks targeting the Egyptian security forces, reportedly carried out by jihadists. Many of the injured are in critical condition.
Alongside the three-month state of emergency, a three-day mourning has also been announced by Egyptian President Abdel Fattah al-Sisi. A night curfew will also be in place.
"The army and the police will take all necessary measures to tackle the dangers of terrorism and its financing, to preserve the security of the region... and protect the lives of citizens," said a statement from the president's office.
The announcement followed a meeting of the National Defence Council which went on for several hours. Headed by the president, the council comprises the prime minister, the defence minister and the chief of the Egyptian armed forces.
The latest attack is the deadliest against security forces in the restive region since former president Mohamed Morsi was deposed last year.
Though no organisation has formally claimed responsibility, the al-Qaida-inspired Ansar Beit al-Maqdis is widely believed to be behind the bombings as the group has carried out similar attacks earlier.
The Rafah border crossing with the Gaza Strip has also been temporarily close in the wake of the attacks.
The US has condemned the attacks. State Department spokesperson Jen Psaki said in a statement: "The United States strongly condemns the terrorist attack that targeted a military checkpoint in the Sinai near al-Arish, and killed tens of Egyptian soldiers and injured dozens. We extend our condolences to the families of the victims, and hope for the quick and full recovery of the wounded."