Thousands of police and soldiers were deployed Monday across the Egyptian capital ahead of planned demonstrations against the government's transfer of two Red Sea islands to Saudi Arabia, a thorny issue which has already sparked the largest protests since President Abdel-Fattah el-Sissi assumed power nearly two years ago. Following the arrest of dozens of activists and journalists in recent days, riot police backed by armored vehicles on Monday took up positions in Cairo's Tahrir Square, the epicenter of Egypt's 2011 uprising, They also deployed on the ring road, downtown and at a square where hundreds of anti-coup protesters were killed when security forces broke up their sit-in in August 2013. Many of the protest organizers' gathering points were sealed off by police, including the doctors' and journalists' unions in central Cairo. Pedestrians near the Press Syndicate were stopped by police, who asked for IDs and about their destination before turning many of them away. The military said in a video released late Sunday that troops were deployed to protect "vital and important installations" and deal with anyone who tries to "harm the people's interests or attempt to ruin their happiness" on Sinai Liberation Day, a national holiday marking the completion of Israel's withdrawal from the peninsula in 1982.

Egyptian warplanes roared over Cairo to mark Monday's anniversary, but the military kept a low profile on the ground except for areas near military headquarters and the presidential palace. The Interior Ministry said police were out in force to protect "peaceful" citizens who wish to celebrate. Several dozen people waving Egyptian flags celebrated with music and dancing in the upscale district of Mohandiseen. El-Sissi on Sunday urged citizens to defend the state and its institutions from the "forces of evil," an apparent reference to the planned protests. Monday's planned demonstrations would be the second wave of protests this month against the decision to give up control of the islands at the mouth of the Gulf of Aqaba. On April 15, about 2,000 people protested in downtown Cairo over the islands.

That protest was the largest against el-Sissi since he assumed office in 2014, nearly a year after leading the military ouster of the Mohammed Morsi, Egypt's first freely elected leader. Chants of "leave," and "the people want to bring down the regime" rang out in the downtown area on that day, harkening back to the 2011 uprising that forced autocrat Hosni Mubarak to step down after nearly 30 years in power. Authorities have detained dozens of activists in recent days, with the arrests continuing until just hours before the planned demonstrations. Freedom for the Brave, an activist group, says nearly 100 people have been arrested since last week. On Monday, at least three journalists were arrested downtown, according to Khaled el-Balshy, a member of the Press Syndicate's board. The Interior Ministry has said that there will be no leniency for anyone breaking the law. Protests without prior police approval have been effectively banned under a law passed months after el-Sissi took power.