Japan has approved the resumption of nuclear power operations at two reactors despite mass public opposition, the first to come back on line after they were all shut down following the Fukushima crisis.
Japanese Prime Minister Yoshihiko Noda, whose popularity ratings have been falling, had backed the restarts for some time.
He announced the government's decision at a meeting with key ministers, giving the go-ahead to two reactors operated by Kansai Electric Power Co at Ohi in western Japan.
The decision, which comes in spite of public concerns over safety after a major earthquake and tsunami crippled the Fukushima plant, could open the door to more restarts among Japan's 50 nuclear power reactors.
"There is no such thing as a perfect score when it comes to disaster prevention steps," Trade Minister Yukio Edano told a news conference after the announcement.
"But, based on what we learned from the Fukushima accident, those measures that need to be taken urgently have been addressed, and the level of safety has been considerably enhanced [at the Ohi plant]," he said.
Mr Edano, who holds the energy portfolio, said the government policy to reduce Japan's dependence on nuclear energy in the medium- to long-term was unchanged despite the decision.
The decision is a victory for Japan's still-powerful nuclear industry and reflects Mr Noda's concerns about damage to the economy if atomic energy is abandoned following the world's worst nuclear disaster since Chernobyl.
The push to restart the two Ohi reactors, before a potential summer power crunch, also underscores the premier's eagerness to win backing from businesses worried about high electricity costs that could push factories offshore.
Kansai electric says it will take six weeks to get both reactors running fully.
As many as 10,000 demonstrators gathered outside Mr Noda's office last night amid a heavy police presence to denounce the restarts, urging the premier to step down and shouting "Lives matter more than the economy."
Mr Noda's own future is unclear as he struggles to hold his fractious party together after cutting a deal with opposition rivals to double Japan's sales tax to 10% by 2015.
Nuclear power supplied almost 30% of electricity needs before the March 2011 disaster, which triggered meltdowns at Fukushima, spewing radiation and forcing mass evacuations.
The accident destroyed public belief in the "safety myth" promoted by Japanese nuclear power advocates for decades.
Activists have collected more than 7.5 million signatures on a petition urging an end to atomic power. Protesters have poured onto the streets almost daily over the past week.
All 50 reactors were shut down for maintenance or safety checks in the months since the accident. The government had placed a priority on gaining the approval of local communities for the Ohi restarts to avert July-August power shortages.
Critics say the government was too hasty in signing off on the restarts, especially given delays in setting up a new, more independent nuclear regulatory agency.