CAIRO -- Islamist militants shot down an Egyptian military helicopter in the Sinai Peninsula with a surface-to-air missile over the weekend, raising new alarms about the terrorist insurgency that developed there in response to the military takeover last summer.
The attack -- described by witnesses, documented in a video released by the militants, and confirmed by three people briefed on the Egyptian government's investigation -- validated long-standing fears that such weapons would spill into Egypt and beyond after the Libyan civil war tore open Moammar Gadhafi's fearsome arsenals.
Known as manpads, for man-portable surface-to-air defense systems, the missiles can bring down commercial airliners if they are flying at low altitude, as during takeoff and landing. They also strengthen Sinai-based militants' hand against the Egyptian army, and there is concern that the militants might seek to use the missiles on the Egyptian mainland, where terrorist attacks have become more frequent. On Saturday, four bombings killed six people in greater Cairo.
Ansar Beit Al-Maqdis, a militant group based in Sinai that has claimed responsibility for an escalating series of attacks on police and soldiers, said in a statement posted on jihadist websites that it had succeeded in "downing a military helicopter with a surface-to-air missile and killing its entire crew in the area around the city of Sheikh Zuweid" in North Sinai, near the border with Gaza.
Witnesses said they had seen "a strange body" flying Saturday toward the helicopter, which then burned in the air for a time before falling. The helicopter landed near El Shollaq, a small town just south of Sheikh Zuweid, and continued to burn for hours. All five soldiers in the helicopter were killed, security officials said.
Israeli officials said they had believed for some time that militants had manpads in Sinai as well as in the adjacent Gaza Strip, controlled by the Palestinian Islamist group Hamas.
In Egypt, news of the attack was almost overshadowed by other political violence. The military-backed government held a celebration Saturday in Tahrir Square to commemorate the third anniversary of the revolt that toppled President Hosni Mubarak, and at least 49 people were killed and 250 injured in clashes with security forces at protests against the military takeover, health officials said Sunday.
On Sunday morning, masked men in an SUV attacked a bus carrying soldiers in Sinai, killing at least three and injuring at least 11, a military spokesman said. On Friday, at least six people were killed in four bomb blasts around Cairo, an art museum was badly damaged, and eight more people died in clashes with security forces.
The violence did not appear to slow the government's brisk transition plan. Adly Mansour, a senior judge and Egypt's interim vice president, condemned the "heinous terrorist attacks" in a seven-minute televised address, but he also accelerated the political calendar. Instead of holding parliamentary elections first as promised, Mr. Mansour decreed, the government will hold presidential elections first, sometime between Feb. 17 and April 18.
He offered little explanation, but the shift was widely expected. It will make it easier for Gen. Abdel-Fattah el-Sissi, who appointed Mr. Mansour as interim vice president, to run for president and consolidate his power before any rival parties or players can find footholds in Parliament.
In an effort to create an atmosphere of celebration for the third anniversary of the revolt -- an event that doubled as a rally for Gen. Sissi -- the government declared the downing of the helicopter an accident until further investigation.