SOFIA -- On the evening of March 21, 2015, around 7:30 p.m., the skies over Iganovo burst into fiery shades of red and orange, and the windows of homes in the tiny Bulgarian village rattled and shook.
Panicked locals rushed to flee from the source of the chaos: explosions at the Vazov Machine-Building Plant, a state-owned facility where anti-tank munitions, antiaircraft missiles, and other weaponry is manufactured.
Only three weeks later, just before dawn on April 14, the village was again rattled by blasts at the same plant, partially destroying one part of the sprawling complex.
The two incidents fit a pattern: four other blasts had taken place over 2014 at various locations in Bulgaria where weaponry and similar munitions are manufactured. At one location, Gorni Lom, northwest of Sofia on the border with Serbia, 15 people were killed.
Bulgarian prosecutors investigated the cause of the blasts, but charges were filed in only one: the October 1, 2014, explosion in Gorni Lom; the four defendants were later acquitted. There is no public information about what happened to the other investigations.
In the wake of this week's revelations about an ammunition-depot explosion in 2014 in the Czech Republic that has been blamed on Russian military intelligence, as well as another suspicious blast at the same depot later that year, one former Bulgarian defense minister called for the Bulgarian investigations to be reopened.
And a new analysis by RFE/RL's Bulgarian Service adds further evidence suggesting a possible link between the Russian military intelligence agency -- known as the GRU -- and the Bulgarian explosions.
At around the time of the explosions at the Vazov plant in the spring of 2015, at least six Russians who have been identified as, or are believed to be, GRU agents were regularly coming and going to and from Bulgaria.
Moreover, flight data and GPS track info, first compiled by the open-source investigation organization Bellingcat, shows another alleged GRU agent traveling in and out of Bulgaria, close to the dates of the 2014 explosions.
The Czech prime minister has blamed the GRU; specifically its elite and notorious Unit 29155.
The unit has also been linked to a near-fatal poisoning of a Bulgarian arms dealer named Emilian Gebrev, whose weapons caches were reportedly the ones destroyed in the Czech Republic.
The first of the two poisonings that Gebrev suffered occurred on April 28, 2015 -- two weeks after the April 14 explosion in Iganovo.
String Of Unsolved Blasts
On February 28, 2014, an explosion at the Arsenal weapons complex in Kazanlak, east of Sofia, partly destroyed a workshop where gunpowder was produced, killing one person.
Six months later, on August 8, 10 people were injured in a series of explosions at the TEREM-Tsar Samuil military plant in Kostenets, in southwestern Bulgaria.
Less than two months later, on October 1, the deadliest disaster to hit a Bulgarian munitions facility struck at the Midzhur plant in Gorni Lom. Aside from the 15 dead, two other people were wounded.
In the third week of December, a private manufacturing company of ammunition and hunting ammunition in Maglizh, in southern Bulgaria, was hit with an unexplained explosion that killed one person.
The explosions all occurred during a period of high tensions in Eastern Europe sparked by Russia's invasion and annexation of Ukraine's Crimean Peninsula, and the outbreak of a Russian-backed separatist war in eastern Ukraine.
At the time, Ukraine's armed forces were in a disastrous state, depleted by a lack of organization, proper training, and a severe shortage of proper weaponry and equipment.
Ukrainian officials struggled to quickly find weaponry and ammunition to hold off the onslaught of better-equipped and better-trained fighters, whose numbers included Russian military operatives.
Bulgaria maintains a sizable arms manufacturing and trade industry.
To this day, despite overwhelming evidence to the contrary, Russia denies having any role to play in the Ukrainian war, calling it an "intra-Ukrainian conflict."
According to flight-tracking data published by Bellingcat, a Russian citizen named Vladimir Moiseyev who used the pseudonym "Vladimir Popov", traveled to Bulgaria on at least four occasions in 2014: in March , September, November, and December, and once in 2015. All those trips occurred in the days around the explosions at the various munitions.
Officials in Montenegro say they are also seeking Moiseyev in connection with an alleged coup plot in 2016. The GRU has been blamed for that failed effort.
Beginning in February and April 2015, meantime, at least six other Russians later alleged to be military intelligence were known to have traveled in and out of Bulgaria, according to flight data. Those identified included Denis Sergeyev, and Sergei Lyutenkov, who traveled to Sofia under the pseudonyms Sergei Fedotov and Sergei Pavlov, respectively.
Another alleged agent named Yegor Gordiyenko who used the pseudonym Georgy Gorshkov arrived in the Black Sea town of Burgas around the third week of April, according to the flight data, along with Sergeyev.
The presence of the two in Bulgaria coincided with two sudden and mysterious illnesses that nearly killed Gebrev, the arms dealer, between April 28 and May 4. Two other Bulgarians, including Gebrev's son, also suffered near-fatal illnesses.
Bulgarian investigators later announced that Gebrev was the victim of "intoxication with an unidentified organophosphorus substance," but did not pinpoint the actual substance or make much known progress in the case until three years later, when a former Russian military intelligence officer named Sergei Skripal and his daughter nearly died after being exposed to a powerful Soviet-designed nerve-agent called Novichok.
British law enforcement later identified two Russian men as the culprits in the poisoning, which also resulted in the accidental death of a British woman.
Those men were later identified by Bellingcat, and subsequently by U.S. and British officials, as being members of Unit 29155, the same unit that many of the alleged GRU agents traveling to Bulgaria are believed to belong to. Czech police have issued an arrest warrant for two Russians having the same names as the two wanted in Britain for the Skripal poisoning, and the photographs released by Czech police are the same used by the British.
In February 2019, Bulgarian investigators reopened their investigation into the Gebrev poisoning; then-Prosecutor-General Sotir Tsatsarov said a suspected Russian intelligence officer linked to the Skripal poisoning was in Bulgaria in April 2015.
Gebrev later told prosecutors he had reason to believe the substance used on him might have been similar to Novichok. In an interview with RFE/RL in February 2019, Gebrev did not name Russia specifically as a co-conspirator in the poisoning, but he said reports of a Russian agent's involvement did not surprise him.
In December, Bulgarian officials said their investigation into the poisonings was focusing on five alleged GRU agents, and the following month they charged three Russians in absentia. The prosecutors identified the three by their pseudonyms; several days later, Bellingcat identified their real identities using a leaked Russian personnel database.
GRU Unit 29155 was specifically named by Czech Prime Minister Andrej Babis in an emergency news conference on April 17 in which he accused the unit of being involved in at least one of the arms-depot explosions in the east of the Czech Republic in 2014.
The ammunition has been linked to Gebrev, who allegedly was arranging to broker a sale with Ukraine as officials there sought to bolster their beleaguered armed forces. Gebrev has denied those allegations.
A top former Ukrainian intelligence official has confirmed that Ukraine was working with a Bulgarian arms dealer at the time.
Todor Tagarev, a former Bulgarian defense minister, said the Czech revelations and new data about GRU agents in Europe absolutely called for a new investigation into the Bulgarian explosions.
"The arms industry is dangerous, there are accidents. But production processes are structured in such a way that in case of an accident there are minimal damages and consequences, but six explosions in less than two years, this is already becoming very dubious," Tagarev told RFE/RL's Bulgarian Service.
"Knowing what the Russian influence is in Bulgaria, what Russian interests are, and how our policy on arms sales and re-exports sometimes contradicts Russian interests, it does not seem illogical to me that there was interference" by Russia, he said.