The Arab world's most populous nation, Egypt has for years been fighting Islamic militants in the northern Sinai Peninsula.
The government had so far succeeded in containing them in that remote and rugged northeast corner of the country and foiled repeated attempts by the militants to seize and keep territory.
But the violence has now spilled over onto the mainland, with an increasing number of high-profile attacks, including a total of four that targeted Christians since December.
The string of attacks has highlighted an ongoing vulnerability and a worrying lack of reliable intelligence by Egypt's robust security forces.
Unlike the attacks in Sinai, which have mostly targeted soldiers, police and suspected collaborators, the attacks on Christians have attracted unwanted international attention and stymied Egypt's desperate efforts to revive its tourism industry, a traditional backbone of its now-ailing economy.
Egypt's general-turned president has, since taking office in 2014, declared uncompromising resolve to defeat the militants. He also seems willing to sideline and disenfranchise almost all Islamic groups with a political agenda, arguing that violent and peaceful Islamic groups feed off each other.
He has backed up his vow to restore security to this nation of 93 million with massive arms deals that added French fighter-jets, helicopter carriers as well as German submarines to Egypt's already huge arsenal of Soviet-era weapons and US-made F-16 warplanes, Apache gunships and Abrams tanks.