A Pakistani military court has issued a death sentence for an Indian man who they claim confessed himself to be a spy from India’s foreign intelligence service.

The man in question is Kulbhushan Sudhir Jadhav, a former officer in the Indian Navy, who was detained by Pakistani authorities in March 2016 and accused of “sabotage and espionage” against Pakistan.

News of the pending execution has outraged Indian politicians and other officials, with the Indian foreign office saying in a statement: “If this sentence against an Indian citizen, awarded without observing basic norms of law and justice, is carried out, the government and people of India will regard it as a case of premeditated murder.” An Indian member of parliament said, “If the sentence is carried out, it will call for very serious escalation on our part too.”

India and Pakistan, like all countries around the world, regularly conduct espionage against each other. The Pakistani intelligence service, the ISI, is all but confirmed as being the major sponsor and coordinator of the infamous 2008 Mumbai attacks which killed 166 people. However, spies themselves are rarely executed, instead usually expelled or used as diplomatic leverage in exchange for other political prisoners.

But if the death sentence is unusual in the case of captured spies, and carries such potentially disastrous consequences with regard to Indian-Pakistani relations, why would Pakistan allow the sentence to be carried forward?

Jadhav was tried and convicted within a controversial Pakistani military court system, one that has been characterized as “inherently abusive” by Amnesty International. It runs essentially parallel to the regular civilian courts, and evolved out of the public’s desire for tougher action to be taken against Islamic extremists within the country. Under the old civilian system, lawyers and judges who prosecuted terrorist suspects were frequently the targets of attack. By handing over judicial responsibilities for security matters to the military, Pakistanis hoped the incompetence of the previous system could be overcome.

However, critics of the military system say trials are conducted unfairly, with no prospect of a fair trial for the accused. Court proceedings are not open to the public, there is no right to appeal, and the defendant has no ability to hire their own lawyers.

Some experts believe the decision to execute Jadhav is a message from the military to the civilian leadership of Pakistan: stop with peace overtures to India. Pakistani Prime Minister Nawaz Sharif and Indian Prime Minister Narendra Modi both made significant efforts to normalize relations between the historically bitter rivals when they assumed office. However, hardliners in both countries have opposed these efforts.