DUBAI — A drone attack that cut off external power to a nuclear reactor in the United Arab Emirates this week has revived concerns over the safety of nuclear plants during wartime.Reactor No. 3 at the Barakah nuclear plant lost vital off-site power for about 24 hours after the attack on Sunday, forcing it to rely on emergency diesel generators.At an emergency UN Security Council session Tuesday, the head of the UN nuclear watchdog described his agency’s “grave concerns” about the growing trend of targeting operating nuclear plants in the Iran war.“In case of an attack on the Barakah nuclear power plant, a direct hit, could result in a very high rate of radioactivity to the environment,” said Rafael Grossi, the International Atomic Energy Agency chief.Addressing the Security Council session, UAE Ambassador Mohamed Abushahab condemned the “unlawful, unprovoked terrorist attack,” and warned that failure by the international community to respond decisively could normalize assaults on civilian nuclear infrastructure.“The attack on Barakah constitutes a dangerous escalation in an already volatile regional environment,” Abushahab told council members.“Threats and attacks of this nature are a red line for the UAE, and we reserve our full and inherent right to protect our territory and population in accordance with international law.”The UAE’s defense ministry said on Tuesday that three drones targeting the plant had originated from Iraqi territory, suggesting a pro-Iranian proxy group was most likely to have been behind the strike.Two were intercepted, but one got through, causing a fire near a four-reactor plant that supplies the UAE with a quarter of its electricity.The UAE said the strike hit an electrical generator “outside the inner perimeter”, raising fears it could have hit the switch yard which lies just beyond a wall around the site’s reactors.No group has claimed responsibility for the attack but Tehran and its militia proxies have launched drone attacks targeting Gulf Arab states since Israel and the United States began their war against Iran on Feb. 28.There were no reported injuries or radioactive leaks at Barakah after the attack.In Iraq, government spokesman Bassem al-Awadi, without mentioning the Emirati accusations, said that Baghdad “expresses its strong condemnation of the recent drone attacks targeting the UAE.”“We also emphasize the importance of effective regional and international cooperation to prevent any escalation or harm to the stability of the region, or any targeting of the security and sovereignty of sisterly and friendly nations,” al-Awadi added.There were three other drones that targeted the country over the last two days, the UAE added, without elaborating on their targets. Saudi Arabia, which had also condemned the nuclear plant attack, later said it had intercepted three drones that had entered the Kingdom from Iraqi airspace.The $20 billion Barakah nuclear power plant was built by the UAE with the help of South Korea and went online in 2020. It is the only nuclear power plant in the Arab world and can provide a quarter of the energy needs in the UAE.