Iran said on Saturday it had executed a dual Iranian-British national who once held a high-ranking position in the country’s defense ministry despite international warnings to halt his death sentence, further escalating tensions with the West amid the nationwide protests now shaking the Islamic Republic.

The hanging of Ali Reza Akbari, a close ally of top security official Ali Shamkhani, suggests an ongoing power struggle within Iran’s theocracy as it struggles to contain the demonstrations over the September death of Mahsa Amini. It also harkened back to the mass purges of the military that immediately followed Iran’s 1979 Islamic Revolution.

Akbari’s hanging drew immediate anger from London, which along with the US and others has sanctioned Iran over the protests and its supplying Russia with the bomb-carrying drones now targeting Ukraine. “This was a callous and cowardly act, carried out by a barbaric regime with no respect for the human rights of their own people,” British Prime Minister Rishi Sunak said.