Ukrainian activists hold a banner reading 'Save Nadia' during a rally demanding the release of Ukrainian officer Nadiya Savchenko from Russian prison in Kiev, Ukraine, 11 July 2014. (Roman Pilipey/EPA)

Mark Feygin is a Moscow lawyer.

At his news conference in Moscow last week, Russian President Vladimir Putin refused to recognize that my client, pilot Nadiya Savchenko, and 30 other Ukrainian service members being held in Russian jails are prisoners of war. This challenge to yet another universal norm demands a strong response from other nations.

Savchenko was captured on June 18 by pro-Russian separatists near Luhansk while on a mission to rescue wounded Ukrainian soldiers. She was dressed in a Ukrainian military uniform and carried a firearm, clearly making her subject to Article 4 of the Third Geneva Convention, which delineates criteria for POW status.

On June 19, a video of her interrogation appeared on the Internet; she was not mistreated but was handcuffed to a metal pipe and questioned on military subjects such as the deployment of Ukrainian forces. Then she was transferred to separatist headquarters in Donetsk, and the chief of rebel counterintelligence confirmed that she had been taken prisoner.

On June 20, the rebels handed Savchenko over to Russian intelligence officers, who put a sack on her head and secretly transferred her to Russia. Russian authorities insist that she crossed the border voluntarily, without documents, in the guise of a refugee — which is a lie.

Savchenko is being held in a civilian prison in Moscow, where she has begun a hunger strike to protest her illegal detention. As Putin confirmed at his news conference, she is accused under the Russian criminal code of complicity in the June 17 killing of two Russian journalists, who died during a mortar attack on separatist positions outside Luhansk. Russian propaganda portrays her as a murderer and a terrorist.

Savchenko’s innocence of this charge can be easily established: Telephone logs show that she was captured an hour before the attack that killed the journalists. But that is not the point. Under the Geneva Conventions, she cannot be charged with a criminal offense at all. If she did anything wrong, she is answerable only to international justice under the laws of war.

Putin’s reluctance to recognize that the Ukrainian captives are POWs is understandable. Russia says that it is not a party to the Ukrainian conflict, even though by the standards of the Geneva Conventions, it unquestionably is. The separatists are armed, trained, supplied and directed by Moscow. In Crimea, Russia occupied and annexed a part of Ukrainian territory. If this does not make Russia a participant in a war, what would? And if it does, my client is Russia’s POW.

But even if the war were solely between the Ukrainian government and the rebels, it is still governed by the Geneva Conventions as an “internal armed conflict” — in which case, Savchenko is a POW of the rebels who has been illegally transferred to Russia. Russia has no business trying foreign combatants under its internal criminal code. If it is not at war with Ukraine, it should release Savchenko immediately.

Whosever prisoner my client is, she is undoubtedly a POW — and has been from the moment of her capture. The Geneva Conventions say that in doubtful cases, the presumption of POW status applies until the uncertainty is resolved by a “competent tribunal.” If Putin respected the law, he would have left the decision on POW status to an independent court before which the Russian state would have the burden of proof.

The international community stops short of naming Russia a party to this war. But sometimes the pursuit of an individual legal case can break through policy constraints and succeed in securing justice. My client has rights under international law, rights that the nations are obligated to enforce regardless of their reluctance to push Putin too far. The International Committee of the Red Cross and the United Nations should demand the immediate release of Nadiya Savchenko and the other Ukrainian POWs — or else Russia should be held in violation of the Geneva Conventions.