Egyptian President Abdel Fattah al-Sisi shortened his trip to Ethiopia Friday after the Egyptian wing of Islamic State, commonly known as ISIS, took credit for killing at least 45 people, mostly soldiers and police officers in the Sinai Peninsula.

According to Reuters, four separate attacks were carried out against security forces in the North Sinai region on Thursday night. It was the first significant assault in the region since a Sinai military group aligned with ISIS in November.

"All of us are in sorrow over what happened yesterday in Sinai but Egypt is paying the price of confronting terrorism and extremism," Sisi said in a statement carried by the state news agency MENA.

His office told Agence France-Presse that Sisi pulled out of an African Union summit in Ethiopia and flew home "to monitor the situation."

Reuters reported that the Muslim Brotherhood has denied any links to the militants. However, the Egyptian government does not make a distinction between both groups.

The group that carried out the attack, according to Reuters, was Ansar Bayt al-Maqdis, which later changed its name to Sinai Province last year after swearing allegiance to ISIS, an ultra-radical Sunni militant group that has occupied parts of Syria and Iraq.

"The army and police will intensify their raids against terrorist and extremist elements in Sinai and across the country," an Egyptian military statement said.

AFP reported that Friday's violent attacks were the deadliest wave of terrorism since October 2014, when 30 soldiers were killed and scores wounded in simultaneous assaults.

The militants justified the attacks as retaliation for a government crackdown on supporters of Mohamed Morsi, the former Egyptian Islamist president and Muslim Brotherhood supporter.

The latest attacks in Egypt's Sinai region have hampered the government's ability to project an image of stability. According to Reuters, although the attacks took place far away from Cairo and tourist attractions, both foreign investors and tourists have been driven away by frequent political violence, which started thanks to a popular uprising four years ago that overthrew autocrat Hosni Mubarak.

"Most of Thursday's casualties occurred in the bombing of a military hotel and base in al-Arish, the heavily guarded Sinai provincial capital," Fick and Mohamed wrote.

AFP reported that U.S. State Department spokesperson Jen Psaki condemned the latest attacks, adding that Washington "remains steadfast in its support of the Egyptian government's efforts to combat the threat of terrorism."

Egypt is considered a vital U.S. ally in the Middle East. According to AFP, Washington delivered 10 Apache helicopters to Egypt late last year as part of joint counter-terrorism operations in the Sinai.