Revival of diplomacy? Ukraine, Russia make progress on prisoner swap.

A deal appears to be in the works between Moscow and Kiev to exchange captured Ukrainian helicopter pilot Nadiya Savchenko, recently sentenced to 22 years in a Russian prison, for two Russian servicemen convicted of "terrorism" in a Kiev court this week.

But while the apparent agreement offers a rare point of light in the frayed relationship between the two countries, it also could reignite the question of just how involved Russia has been and continues to be in the restive Donbass region of Ukraine.

Ukrainian President Petro Poroshenko announced that an "algorithm" had been agreed to facilitate the possible exchange of Ms. Savchenko, which could happen in the next few days. Mr. Poroshenko and Russian President Vladimir Putin held a reportedly constructive telephone conversation about the prospective swap, a marked return to diplomacy in bilateral relations after two years of war, both hot and cold.

The repatriation of Savchenko, whose defiance of her Russian captors has earned her national hero status and a place in the Ukrainian parliament, would remove one of the most prominent irritants in the "information war" between the two. It may also help to improve Russia's image in Europe, where support for renewing anti-Moscow sanctions in July is already looking shaky. But it comes as the conflict is once again escalating along the battlefront in eastern Ukraine. 

Savchenko, a helicopter pilot who left the Ukrainian Army to fight with a pro-Kiev volunteer battalion two years ago, says she was captured on the battlefield by rebel forces and illegally transported to Russia, where she was charged with the murder of two Russian journalists. She denied the charges, put up a steady show of defiance in the courtroom and literally laughed when the judge read out her sentence. She also launched a hunger strike, which she suspended on Tuesday when Mr. Poroshenko personally called and asked her to do so.

Russia in the Donbass

The circumstances around the two Russians, Alexander Alexandrov and Yevgeny Yerofeyev, who were captured in combat in east Ukraine last year, are murkier than those around Savchenko.

Ukrainian experts insist that the Kremlin's willingness to negotiate for them is proof that they were regular Russian troops, part of a large invading force that tore Ukraine apart following the Maidan Revolution in early 2014, even as Moscow denied any direct involvement. The two men initially admitted to being operatives of the GRU, Russian military intelligence, but later retracted those confessions and said they were just ex-military "volunteers" with the Ukrainian rebels.

Their return to Russia under the proposed deal will probably reignite that vexing question. While the standard Ukrainian narrative argues that separatism in the eastern region of Donbass following the Maidan Revolution was entirely Moscow-made, the actual extent of Russian intervention has proven extremely difficult to pin down. And Russian experts argue that the case of Mr. Alexandrov and Mr. Yerofeyev is no smoking gun.

"Of course there is no way that ragtag rebel army could have defeated the Ukrainian forces in those decisive battles around Donetsk in 2014 and early 2015 without Russian help," says Sergei Strokan, international affairs columnist for the Moscow daily Kommersant. "But the Russian side has developed this legal formula, which says that lots of Russian 'volunteers' crossed over to help the rebels, but no regular Russian troops."

"You may say it's a distinction without a difference, but it lets Russian authorities off the hook," says Mr. Strokan. "Arguing over it has already proven to be a dead end."

Political wins

Both cases have proven problematic in their execution. The Savchenko trial was perceived around the world as politically motivated, and human rights experts say it was riddled with irregularities. The trial of Alexandrov and Yerofeyev was marred by the grisly abduction and murder of Alexandrov's lawyer, presumably by Ukrainian ultra-nationalists.

As such, the resolutions a swap would bring will likely benefit both sides – at least politically.

"Putin should be glad to get rid of Savchenko, because her case attracted too much attention and she became a symbol of Ukrainian resistance," says Viktor Nebozhenko, director of the independent Ukrainian Barometer sociological agency in Kiev. "Both presidents will gain a big PR victory from this. In Russia they will launch a big campaign declaring 'we never leave our people behind,' and the same thing will happen here [in Ukraine]. On the eastern front, however, it won't change a thing. People will go on dying every day."