Pro-Russian separatists and Kyiv's forces are observing a cease-fire in many parts of eastern Ukraine.
Yet, around Donetsk airport, there is not even the pretense of honoring the truce that is supposed to pave the way for ending the conflict.
Night after night, separatists in neighborhoods near the airport shell army positions inside the airport perimeter. The soldiers respond with fire of their own, hitting the residential areas where the militiamen set up rocket-launchers, howitzers, and mortars, shoot, and rapidly shift position again.
As the airport, just 10 kilometers from the city center, progressively disintegrates under rebel fire, the control tower has become a useless hulk and the runways are strewn with shell holes. But the battle continues because the separatists see the airport as having huge symbolic and strategic value.
"The separatists are very much interested in the preservation of the so-called independence of their republics," says Igor Sutyagin, a specialist on Russia's military at the London-based Royal United Services Institute (RUSI).
"And if you wish to be an independent country recognized or not, you need a large airport to have connections with the outer world."
At the same time, the airport has continuing military importance.
"In terms of its direct military value, there is an issue as to the state of the runway itself, since it has been under artillery fire for some time," says Douglas Barrie, a military expert at the International Institute for Security Studies (IISS), a security think-tank in London.
"But you can repair runways pretty quickly and get them up to useable condition in reasonable speed and this would open up a corridor for defense material to be flown in" for the rebels.
He notes that the separatists also want to control the airport to make sure Kyiv cannot use it ferry in supplies of their own to create a military base that would threaten the separatists' self-declared capital.
Rebel Air Force?
There is still another reason that the separatists are keen to get control of the airport and that is to open up the possibility of getting fighter jets that would give them greater military parity with Kyiv.
Whether or not they could get fighter planes depends entirely upon Moscow.
But there are some signs that Moscow has considered the idea as it keeps its options open.
These include seeing the separatists gain autonomy within a united Ukraine, freezing the conflict and creating a de facto Russian protectorate in Donbas similar to Georgia's Abkhazia and South Ossetia as well as Moldova's Transdniester regions, or engineering outright independence for the region and potentially incorporating it into Russia.
"The Kremlin is not fully embarked on the idea that these republics would be just autonomous within Ukraine," says Sutyagin.
"There is still some desire to have them independent from Ukraine, in which case it would be very important to preserve their military independence and defendability and that is why there were some plans and even some preparations to arm the rebels with combat aircraft."
A Ukrainian group called Information Resistance, which includes former military officers and monitors the situation in eastern Ukraine and adjacent areas of Russia, reported last month that it had spotted unmarked combat jets at air bases in Russia's Rostov-on-Don region.
Analysts say that repairing the damaged Donetsk tarmac sufficiently to take fighter planes would be easy because combat jets need a runway of just 500 to 600 meters length. The full Donetsk runway is about 4 kilometers long.
The major obstacle to the rebels' using the Donetsk airport for military purposes would be the danger that Ukraine's forces could shoot down incoming and outgoing planes.
"The Ukrainians have within their inventory a number of short, medium, and indeed long-range surface-to-air missile systems," notes Barrie. The long-range systems include early models of the S-300 and also the Buk, the same system which Western officials believe separatists used to bring down Malaysia Airlines Flight 17 over eastern Ukraine in July.
That means the rebels would have to control territory beyond the airport to at least a distance of 5 kilometers to protect against shoulder-fired missiles. They would also need to have sophisticated radar jamming stations near the airport to protect airplanes from radar-guided long range missiles fired from up to 90 kilometers away -- which could only be provided by Moscow.
Just how important control of airports can be in deciding the outcome of post-Soviet separatist wars has been amply demonstrated before.
In 1992, Russian General Alexander Lebed seized the airport at Tiraspol in Moldova's breakaway region of Transdniester and used it to reinforce pro-Moscow separatist forces there. The four-month conflict ended shortly afterward with a cease-fire brokered by Moscow. Transdniester retains de facto -- albeit widely unrecognized -- independence under Russia's protection to this day.
