Securing the edge: From Ukraine to the Baltics, a new line of defense rises against Russia

"Modern combat structures are usually made from precast components like reinforced concrete, HESCO gabions, or from traditional materials such as wood supplemented with soil or sand," explains Aleksander Fiedorek, a specialist in protective construction. "Various material combinations are utilized, like a bunker constructed from precast concrete elements, covered with HESCO gabions filled with sand. Elements characteristic of armored combat vehicles' construction appear in the field fortifications, such as rod screens and anti-fragmentation interiors," the expert elaborates.

Initially, Ukraine had wooden blockhouses fortified with sandbags. However, they are being increasingly replaced with prefabricated combat shelters made from reinforced concrete. These first appeared in Donbas, and in such locations as Avdiivka, Marinka, or Toretsk, and are now being installed in regions with a high likelihood of Russian attacks, such as Kharkiv and Chernihiv.

Constructing fortifications along the border with Russia isn't a novelty. Poland began renovating and upgrading fortifications along its border with the USSR during the mid-1930s. However, the effort and scale were not sufficient in time, and ultimately, the "Baranovichi" Fortified Area was inactive in 1939.

Finland, on the other hand, was successful in constructing the Mannerheim Line. Despite having just around 150 reinforced concrete combat shelters, the Line made use of natural barriers like marshes, narrow strips of land between lakes, and hills about 15-25 miles away from the border. These fortifications played a key role in halting Soviet advances during the Winter War.

Partly due to the effectiveness of these fortifications during the Winter War, and since the onset of Russian aggression against Ukraine, Finland has been reinforcing and expanding their facilities along their 807-mile border with Russia.

The Baltic countries, given their fraught history with Russia, are also incorporating lessons learned from the Finnish experience.

On Friday, January 19, 2024, Hanno Pevkur, head of the Estonian Ministry of Defense, announced at a press conference in Riga that Lithuania, Latvia, and Estonia have agreed on constructing a common defensive line along their borders with Belarus and Russia. The planned defensive line will span roughly 435 miles.

Pevkur stated that the war in the east has demonstrated the need for "physical defensive structures at the border" in addition to equipment, ammunition, and manpower. He mentioned plans for constructing over 600 combat shelters in Estonia alone, designed to house up to ten soldiers and all their armament.

"Field fortification is vital, especially for the Baltic countries, which lack operational depth and for whom making up for any territorial losses will be extraordinarily difficult. In the event of conflict and given NATO's air superiority, these fortifications would slow down a Russian offensive, lessen its strength and direct the attack course," explains Aleksander Fiedorek.

"This would aid defensive operations, reduce our losses and increase enemy losses and operational costs. Substantial forces, considerable artillery, and air support are required to breach defense based on fortifications," the expert assesses.

Kaido Tiytus, an adviser to Minister Pevkur, presented the building plans for combat shelters. The structure, a blend of steel and concrete, will be arranged in a 'T' shaped trench line, camouflaged with vegetation, and designed to withstand a direct hit from a 152 mm caliber projectile.

"We're using steel doors and shooting shields and placing significant emphasis on crew comfort. The infrastructure includes bathrooms, toilets, and comfortable sleeping arrangements, particularly in passive objects - structures without shooting stations that are usually located deeper underground than combat structures," Fiedorek explains.

The report published by Estonia's Ministry of Defense states that the fortifications "take into consideration the results of enemy and environmental analysis and defensive force combat plans. The Baltic countries work as one operational area, thus the construction of defensive structures is coordinated with Latvia and Lithuania."

The estimated construction cost is 60 million euros (approximately 67 million dollars) and work is slated to begin early next year at the latest.

Details of the Latvian and Lithuanian plans have not yet been disclosed. However, it is known that the entire line of fortifications should be integrated into a single system. Consequently, Latvian president Edgars Rinkevics called on NATO allies for cooperation.

"If we desire an effective defense mechanism, cooperation is vital between neighboring countries Finland, the Baltics, and Poland," said the president, as quoted by the LETA agency.

Currently, the Polish border with Belarus is primarily safeguarded by a fence, whose effectiveness has been criticized. The border with the Kaliningrad region is "protected" by only lakes and a modest road network. The Polish Ministry of Defense does not currently have plans to construct fortifications.

Gen. Wiesław Kukuła, Chief of the General Staff of the Armed Forces, praised Estonia's initiative in an interview with the O2 portal, but stopped short of discussing similar plans for Poland.

Should Poland join the Baltic initiative?

"Preparing at least part of the fortification objects in advance is beneficial, even if it just involves storing prefabricated construction elements in predetermined places. Even without actual building, planning these actions and securing the materials for execution during peacetime can drastically reduce the time needed to prepare fortifications during periods of heightened international tension. Given the current situation, we should already be initiating the planning and construction process," Fiedorek emphasizes.

Since the 1930s, Polish engineers have not constructed fortification lines. Any potential plans for future construction would have to take into account experiences from Ukraine, but also from Finland and Czechoslovakia in 1938. Both countries lost their fortifications, which were located too close to the border.

"A Polish line of this nature should be situated further from the border," the expert advises. "The border area should be prepared for the destruction of road and bridge structures, forest obstructions, and minefields. These areas should be thoroughly scouted. The defense line should be deep, comprising a minimum of 3-4 layers, with barriers, engineering hurdles, and minefields."

"Both prefabricated and lighter, wooden elements should be used in the construction. The design should also consider the potential use of weapons of mass destruction. The structures should be camouflaged, designed to conduct circular defense, capable of mutually supportive fire. Locations for hiding vehicles, medical facilities, and logistics structures, as well as other assets aiding in defense, should all be fortified," Fiedorek recommends.

"However, I don't support the peacetime laying of minefields 'just in case.' This is far too dangerous for civilians, particularly for children and animals. We should certainly keep large stocks of anti-personnel and anti-tank mines, both conventional and remote-controlled, but their use should be limited to situations of heightened international tension and observable indicators of impending aggression," concludes Aleksander Fiedorek.