Police found two viable explosive devices in residential streets in west Belfast on Saturday.
A security alert sparked by what police called a "suspicious object" in Glencolin Walk lasted several hours, ending shortly before 10pm.
The Police Service of Northern Ireland (PSNI) tweeted: "Security alert at Glencolin Walk, Belfast has ended. Suspicious object declared viable device. Glen Road has been reopened."
Earlier, homeowners were evacuated as specialist officers removed another "viable device" from Ramoan Drive.
Inspector Mark Cavanagh said: "ATO (ammunition technical officers) examined a suspicious object and declared it a viable device. It has been taken away for further examination."
The first alert was declared over at around 3pm.
Sinn Fein MLA Alex Maskey condemned those behind the scares, which come after a prison guard was injured in a bomb attack in the east of the city on Friday.
He said: "Devices were left close to two homes in west Belfast over the last 24 hours.
"I condemn unreservedly the people behind these attacks who have succeeded only in putting the lives of local people at risk and bringing disruption to the community.
"It's understood these attacks are linked to a despicable attempt at extortion by a criminal gang masquerading as Republicans.
"These people should end their criminality now and get off the backs of the community."
A 52-year-old prison officer, a married father of three, required surgery after an explosive device detonated under the van he was driving to work on Friday morning. His condition is described as stable.
Police commanders have expressed fears it may be the first of a number of dissident republican murder bids launched to mark the centenary of the Easter Rising.
PSNI assistant chief constable Stephen Martin said he was extremely concerned about an upsurge in dissident activity ahead of the forthcoming 100th anniversary of the republican rebellion against British rule in Dublin.