The State Bureau of Investigations (SBI) has said it established the reasons and conditions that contributed to the collapse of the Armed Forces of Ukraine and annexation of Crimea by Russia.

"In particular, criminal actions to undermine the combat capability of the Ukrainian army began in 2012 and continued until the invasion of Russian military units into the territory of the Autonomous Republic of Crimea in February 2014. The highest state officials of that period are suspected of committing high treason - fugitive President Viktor Yanukovych, ministers of Defense of Ukraine Dmytro Salamatin and Pavlo Lebedev, as well as Chief of the General Staff of the Armed Forces of Ukraine Dmytro Salamatin," the SBI said on its website on Wednesday.

SBI investigators identified five main episodes of the crime, which ultimately led to the occupation of the Crimean peninsula:

1) Criminal reduction of the armed forces. "Despite the return to a non-aligned status, which required an increase in the size of the army, during 2012-2013 the maximum number of Ukraine's Armed Forces was reduced from 240,000 to 162,000 servicemen," the SBI said.

2) Undermining the state of mobilization readiness. "In 2013, half of the regular number of military registration and enlistment offices was reduced. As a result, military units were staffed by only 25-55%. In addition, the letter-by-letter assignment of mobilization resources to military units was curtailed and the registration of military equipment was destroyed," the information says.

3) Destruction of Crimean air defense systems. "Control of Crimean air defense system was transferred to the command of the Ukrainian Navy on the peninsula, which later went over to the enemy's side. In addition, one of the two S-300V air defense brigades in service was reduced and the modernization programs for the S-125 and S-200V air defense systems were stopped."

4) Illegal organizational changes and leveling of strategic defense documents. "The large-scale organizational changes of the UAF carried out in 2013, contrary to the law, were not included in the strategic defense documents of the country, which prevented the UAF from forming a strike group and protecting the territorial integrity of Ukraine at the time of the implementation of one of the scenarios of external aggression," it says.

5) Failure to take measures to respond to external threats. "Despite numerous intelligence reports that clearly indicated the preparation of an offensive operation by Russia in late 2013 - early 2014, no measures were taken by the UAF to bring forces to the highest levels of combat readiness, organize territorial defense and conduct large-scale military exercises on the territory of Crimea," the SBI said.

The SBI said these reasons and conditions are connected and led to grave consequences – Russia's invasion of Crimea and the city of Sevastopol, their subsequent occupation and violation of the sovereignty and territorial integrity of Ukraine.

The SBI said it continues to conduct investigation into other facts that led to the occupation of part of the territory of Ukraine in 2014.