The announcement was made on February 13 by the Ukrainian Minister of Foreign Affairs Dmytro Kuleba. On his Twitter page, he mentioned that Russia failed to respond to the previous request, which was meant to provide Ukraine with sufficient explanation on the objectives, precise location, dates of completion, and other information concerning the military activities in areas along the Ukrainian border and in Crimea.
Read more: Russia Has 48 Hours to Explain its Military Activities – Ukrainian Foreign Minister
"If Russia is serious when it talks about the indivisibility of security in the OSCE space, it must fulfill its commitment to military transparency in order to de-escalate tensions and enhance security for all," said the official.
The announcement has already been met by the U.S. Mission to OSCE: "The United States stands with Ukraine and calls on Russia to explain its military buildup, as called for in the Vienna Document. The time for transparency is now".
Though neither OSCE nor Russia have given any official answers yet. The OSCE Chairman-in-Office Zbigniew Rau is visiting Moscow this Tuesday. According to the press release by OSCE, one of the major subjects to discuss is stabilizing the security situation and easing tensions in the OSCE region. Russian Ministry of Foreign Affairs in their announcement emphasized the "necessity of the direct dialogue between Kyiv, Donetsk, and Luhansk as the parties to the conflict". Ukrainian minister Kuleba earlier stated that such dialogue is unacceptable and the issue could only be resolved through direct talks with Moscow and President Vladimir Putin.
As Defense Express previously reported, Ukraine has officially triggered the risk reduction mechanism provided by the Vienna Document. Part III of this document contains the mechanism for consultation and co-operation, which provides any participating state with the right to receive a detailed explanation of any unusual and unscheduled activities of their military forces outside their normal peacetime locations. The initial appeal for explanations was made by Dmytro Kuleba on February 11. Russian Ministry of Foreign Affairs stated that they didn't find the request "reasonable".
Ukraine is concerned over Russian military activities along its borders in Russia, Belarus, and in temporarily occupied territories of Crimea and Donbas (Eastern Ukraine). A few days ago, joint Russia-Belarus drills began, featuring an estimated number of 30,000 Russian troops and heavy military machinery.

The international community is worried, too. Multiple countries warned that the invasion of Ukraine would lead to significant costs to Russia. The news media share analytics on possible Russia's invasion. The US provides regular ammunition and military equipment supply to Ukraine. So do the UK, Canada, Lithuania, Poland, and the Czech Republic etc. The total amount of support Ukraine received to deter Russia is over $1.5B, 1000 tons of weaponry, ammo, and equipment.
Read more: Weaponry Received by Ukraine from US and EU Allies Explained