The exact relationship between Yerevan and the Armenia-backed separatist military force in Azerbaijan's breakaway territory of Nagorno-Karabakh is murky.
Independent researchers say it is very difficult to obtain analytically solid details about the exact size of the so-called Nagorno-Karabakh Army or the source of some of the separatist fighters' weaponry.
But the general perception is that there are political, economic, and military links with Yerevan -- and that the Armenian government supports ethnic Armenian fighters who have controlled the territory since the end of their separatist war against Azerbaijan in the early 1990s.
Close examination of the separatist force does reveal some military ties with Yerevan, as well as political synergy.
But Armenia's government insists it has not deployed any military subunits on the territory of Nagorno-Karabakh.
Both Yerevan and Nagorno-Karabakh's self-declared, internationally unrecognized leadership maintain that the separatist forces solely comprise ethnic Armenian fighters from the breakaway region.
But the conclusions of independent Western experts -- including researchers for the British Defense Ministry, the International Crisis Group (ICG), and the British-based International Institute for Strategic Studies (IISS) -- cast doubt on those claims.
'An Open Secret'
In a 2008 research paper published by the Defense Academy of the United Kingdom, C.W. Blandy stated that "several battalions" of the Armenian Army were "deployed directly in the Karabakh zone on occupied Azerbaijani territory."
Blandy also reported that Yerevan supplied weapons and other military necessities directly to authorities in Nagorno-Karabakh's capital, Stepanakert.
He said military training provided by officers from Armenia's armed forces to the Nagorno-Karabakh separatist ranks was "an open secret."
Finally, Blandy maintained that, in 2008, more than half of the 20,000-strong Nagorno-Karabakh force comprised citizens of Armenia.
The IISS's Armed Conflict Database currently states that "Armenia continues to occupy Nagorno-Karabakh and seven areas around it, all internationally recognized as part of Azerbaijan, while Armenian and Azerbaijani forces face off along a 'line of contact' stretching for more than 100 kilometers."
Richard Giragosian, director of an independent Yerevan-based think tank called the Regional Studies Center, agrees that military training and education provided to Nagorno-Karabakh's forces by officers from the Armenian Army is "an open secret."
But he says there also is a "careful distinction in the operational command" of the separatist army. Nagorno-Karabakh's separatist forces control the territory and maintain a security belt of occupied Azerbaijani territory under their own independent chain of command -- a command structure that is separate and distinct from the Armenian Army.
Giragosian says that command structure is a by-product of the pursuit of independence by ethnic Armenian separatists in the enclave. Even before the 1994 cease-fire deal was reached with Azerbaijan, early attempts to convert local ethnic Armenian paramilitary groups into a unified standing army were well under way.
Still, Giragosian notes that Yerevan's state budget officially allocates financial subsidies to Nagorno-Karabakh's breakaway government.
The exact amounts and purposes of those subsidies are not transparent.
'A Very Close Relationship'
Key political figures in Armenia also played an important role in the founding of the "Nagorno-Karabakh Army" in May 1992. Among them are Armenia's former President Robert Kocharian, a native of Nagorno-Karabakh who served as the commander in chief of the Nagorno-Karabakh Army and also served as prime minister and president of the territory's self-declared government.
Armenia's current president, Serzh Sarkisian, is also a native of Nagorno-Karabakh who played a key role in bringing together disparate local paramilitary forces in the early 1990s to create the Armenian-backed, unified military force.
Giragosian says the links between senior Armenian government officials and the Nagorno-Karabakh force are revealing.
"The relationship is based on a bilateral synergy," he says. "[Even] the current defense minister of Armenia is actually the former defense minister of [the self-declared government] of Nagorno-Karabakh. And the formulation of the national security of Armenia takes into account security demands and expectations of Nagorno-Karabakh proper. So there is a very close relationship and synergy."
In terms of military equipment, however, experts say there is not much evidence suggesting that Armenia has been sending modern hardware into Nagorno-Karabakh -- particularly the latest armor and artillery that Yerevan has been purchasing from Russia since Moscow and Yerevan signed a cooperation agreement in 2014, or under a $200 million loan provided in 2015 by Moscow to Armenia so it could purchase modern Russian weapons.
Most of the estimated 200 to 300 battle tanks and artillery pieces held by the Nagorno-Karabakh separatists are thought to be refurbished combat vehicles left behind in the early 1990s by retreating Azerbaijani forces. There have been no sightings of modern Russian-built T-90 tanks. However, some of the Soviet-era T-72 tanks used by the Nagorno-Karabakh separatists have been improved with modern upgrades.
An IISS assessment called The Military Balance, which was published in February, says some of the forces' equipment may belong to Armenia's military.
The IISS assessment also says the Nagorno-Karabakh separatist force's overall personnel strength remains at an estimated 18,000 to 20,000. But it also is thought to have another 20,000 to 30,000 reservists on standby and prepared for quick mobilization.