For the last few days all media attention on the Ukrainian crisis has been focused on two topics: the advances made by Ukrainian forces around the city of Donetsk and, more worryingly, the threat of Russian invasion under the guise of “humanitarian intervention.” What has not been discussed anywhere near as much is that Ukraine has just abandoned control of over 100 kilometers of their border with Russia.

For 22 days, Ukrainian forces along the border with Russia, occupying an area of the Ukrainian ‘Anti-Terrorism Operation’ zone known as Sector D, had been completely encircled by hostile forces. From the west and north, in Ukrainian territory, they were relentlessly harassed and shelled by separatist fighters, while they were shelled with rockets, mortars and artillery from across the Russian border to their east and south. On August 6, Ukrainian forces broke out of their encirclement and linked up with advancing forces from the east near Saur-Mogila, a kurgan summit that has been a key battleground in recent weeks. Having finally re-joined the main body of the Ukrainian forces, the beleaguered defenders of Sector D were evacuated.

The area was guarded by soldiers from the 72nd, 24th and 51st mechanized brigades, the 79th airborne brigade, the third Special Forces regiment and personnel from the State Border Guard Service of Ukraine. Their withdrawal has been hailed in some quarters of Ukraine’s media as an achievement and, as far as the soldiers themselves are concerned, it certainly is. Without relief or resupply from behind the lines and under constant attack on all sides, the outlook for the troops within this narrow strip of land was bleak.

For the last few weeks, the Ukrainians have reported nocturnal attacks on positions in this area almost every morning. Until Ukrainian forces pushed on Saur-Mogila from the west, the hilltop was the firing point for artillery barrages on positions near Marinovka, at the western edge of Sector D. Towns to the north of this slim strip along the border had been taken by separatist fighters, reinforced by Russian-supplied armor. On June 4 separatist fighters seized the border guards’ base in Sverdlovsk while armored personnel carriers lurked in the forest near Provalye. The Ukrainian forces were effectively limited to a handful of villages and small towns scattered along a section of the Russian border approximately 120 kilometers long. Between separatist-held Sverdlovsk and Krasnopartizansk, defended by Ukrainian troops, lay less than 5 kilometers.

Ukrainian forces in this area have also been regularly shelled from Russian territory. Positions near Krasnopartizansk, Dyakovo and Marinovka have reported regular Grad rocket attacks and shelling from across the border. The attacks on Krasnopartizansk came as video footage emerged of Grad rocket launchers near the Russian town of Gukovo, less than 10 kilometers away, firing westwards. These videos were geolocated by The Interpreter on July 16. The Ukrainian Security Service and the US State Department have both since released satellite imagery demonstrating the presence of Russian artillery and rocket launchers on the border, and impact craters near Dyakovo, just to the north of these launch sites.

It was from the narrow corner of Sector D between near the Dolzhansky border crossing, just to the south-east of Krasnopartizansk, that 438 Ukrainian paratroopers and border guards were forced to flee into Russian territory on August 4. According to the Ukrainian military, the servicemen had been under heavy attack from separatist fighters. The soldiers, from the 72nd mechanized brigade, had been surrounded by militants but managed to break out to the east while the remainder of their group provided covering fire. The breakout group found themselves stuck against the border and eventually ran out of ammunition. They were forced to seek shelter from the attacks in Russian territory near Gukovo.

Russia attempted to make use of these men for propaganda purposes, initially claiming that they had asked for asylum as they were unable to follow their orders from Kiev to fight their fellow Ukrainians. A BBC television interview with some of the soldiers in Gukovo, who clearly had no desire to remain in Russia, somewhat undermined an attempt to stage manage the situation by ferrying in journalists in a military convoy. All bar five of the men were returned to Ukraine within days. The first group of whom were mysteriously attacked behind Ukrainian lines near Olginka on August 5. None were killed and Ukraine called the incident an attempt at a provocation.

The remaining five officers were then detained by Russian authorities. Vladimir Markin, the spokesman for Russia’s Investigative Committee (SKR) said that the men were being investigated on suspicion of committing war crimes inside Ukraine. Russia claims that the 72nd brigade has indiscriminately shelled civilian areas and that the men they have detained bear responsibility for this. It appears that the Russian Investigative Committee can act as an international war crimes court when it suits the interests of the Kremlin. Furthermore, Markin said that the SKR would investigate whether the men were responsible for the shelling of Russian territory (as the Kremlin claims has happened in recent weeks) and the use of white phosphorous shells on civilian areas (a claim that has previously been put forwards by Russian state media using old footage from Iraq).

Escaping from this lethal trap took three days of fighting and major logistics. According to Yuri Butusov of Censor.NET, the Ukrainian Air Force played a key role in the evacuation, making regular sorties despite the presence of surface-to-air missiles, including both shoulder-launched Igla missiles and larger, more dangerous, self-propelled SA-10 Strela systems. The personnel in Sector D gathered as much of their surviving equipment as possible and moved west, some in their own military vehicles, others in a convoy of buses. Ukrainian sources claimed that all equipment that could not be moved had been destroyed, however photos uploaded to the pro-separatist Colonel Cassad blog showed relatively undamaged APCs and border service vehicles left abandoned while others, including tanks, lay crashed or burnt out. The photos also appear to show a number of both dead and captured Ukrainian servicemen.

According to Butusov, six border guards and three soldiers were killed during the breakout. Figures for captured soldiers have not been reported by the Ukrainian military. On August 9, Russia’s state-owned RIA Novosti news agency claimed that a “high ranking source in the Ukrainian Ministry of Defence” had said that 3,500 Ukrainian servicemen from Sector D were unaccounted for. The report however claimed that “in the last two weeks, only four groups of seven to 18 people have left the encirclement.” If these comments are at all accurate, they certainly appear to have been made before the withdrawal, and their number could well be exaggerated for propaganda purposes.

The withdrawal has however seriously weakened the Ukrainian forces’ strategic position. Beforehand, the only point of ingress for Russian armour deliveries to the separatists was the crossing between the Russian town of Donetsk and the Ukrainian town of Krasnodon. Numerous convoys of armour and artillery have been spotted and filmed moving through Krasnodon and along one of two routes: to the north via Lugansk to Yenakievo and on to Gorlovka, Makeyevka or Donetsk; the southern route goes via Krasny Luch, and Torez, south of the MH17 crash site, to Donetsk. Donetsk has been cut off from both of these main routes since Ukrainian forces took Debaltsevo and launched an offensive on Shakhtyorsk and, later on, Krasny Luch. Vehicles doubtless still pass through the many side-roads in the area, but the two trunk routes from the border are both blocked.

The withdrawal from Sector D leaves several other border crossings open. A number of these are only minor crossings, connecting tiny rural roads, however the Dolzhansky crossing lies on a major highway route that passes through Antrasyt, passes just to the north of Krasny Luch and then through Debaltsevo. This route could well be used by armoured columns to either outflank Ukrainian forces or to reinforce separatist militants fighting in the Krasny Luch area. The Krasnopartizansk crossing lies on a smaller road, but could be used to massively reinforce the area around Sverdlovsk, and to send reinforcements via Rovenky and Antrasyt to Krasny Luch.

The previous routes from Krasnodon are shown in the map below in green. The Dolzhansky route is red, and the Krasnopartizansk routes are in orange:

Neither of these new routes can aid separatists fighting to hold on to Donetsk, but they may enable the Russian-backed separatists to fend off Ukraine’s recent advances in the southern area of the ATO zone, or even to mount counter attacks on Debaltsevo, with the aim of freeing up resupply routes to Donetsk. It is also far easier now to maintain supplies to, and maintain a broad front around Lugansk, the capital of the self-proclaimed Lugansk People’s Republic, and doubtless the next symbolic stronghold should Donetsk fall to government forces.

Most worrying of course, is the possibility that, rather than passing covertly into Ukraine under the guise of a single ‘humanitarian convoy’ such as that which departed late on August 11 for the border, Russian ‘peacekeeping’ troops may just flood in across the wide stretch of unsecured border and make their presence an established fact before Ukraine can respond militarily or diplomatically. Shooing Russia away from crossing the border is one thing for the European Union and the United States, persuading them to remove their tanks is quite another, as the futility of so many statements of grave concern regarding Russia’s lightning-speed takeover of Crimea has shown.