Perceptions are important, but we need to put in context the events.
Former US Ambassador in Moscow (1987-1991), Jack Matlock, said that “Russian President Vladimir Putin is acting in response to years of perceived hostility from the US, from eastward expansion of NATO to the bombing of Serbia to the expansion of American military bases in eastern Europe”.
Ambassador Matlock most probably is right about Russia’s perceptions, but the problem is reality, or, at least, the perceptions of non-Russians. Talking about Russian feelings about their national interest, in his interview (look at 13:40-15:00 of the video) he argues, among other things, that NATO bombing of Serbia, a country that did not attack any NATO country [true, but Serbia’s politics did affect directly NATO’s countries], and the detachment of Kosovo from Serbia [yes, but Kosovo is still under UN resolution 1244] are very relevant today.
Nevertheless, before NATO bombing in 1999, we had a tragedy called Bosnian War, 1992-1995, with more than 100,000 casualties and, in 1995, at least 1.2 millions Bosnians internally displaced. Still at the end of 2001:
roughly 650,000 Bosnians remained uprooted as a result of the ethnic conflicts of the 1990s. These included about 210,000 Bosnian refugees outside the country in need of durable solutions and about 438,500 internally displaced persons inside Bosnia.
While the (real) war started on Croatian soil in 1991, we had to wait 4 long years before US decided to broke a peace agreement in Dayton. In the meantime, the so called international community sent UN troops and various aids to the civil population, without taking a position, and letting happen Srebrenica and other atrocities.
Notwithstanding speculations and conspiracy theories, notwithstanding the international law, the (virtual) sovereignty of countries, what was the alternative? To let happen, after a few years, the same atrocities, with thousands of victims, displaced persons, refugees, once again? To risk a civil war in Macedonia? What did Russia’s government?
On March 24, 1999, Primakov was heading to Washington, D.C. for an official visit. Flying over the Atlantic Ocean, he learned that NATO started to bomb Yugoslavia. Primakov decided to cancel the visit, ordered the plane to turn around over the ocean and returned to Moscow – it was called Primakov’s loop.
This is just a piece of example about the “perception” of the US administration at the time (click on the below image to enlarge it):
It states: “averting a humanitarian catastrophe in Kosovo and promoting a political settlement”. After all what happened in Croatia and Bosnia and Herzegovina, it was at least a reasonable point of view. Bill Clinton did not have a plan to annex Kosovo to the USA, as someone else did recently with Crimea. Finally, Kosovo did not merge with Albania, as Republika Srpska did not merge with Serbia. If the USA had wanted to go eastward expanding NATO, they could have settled peace, forcing the situation on the ground, well before 1999. They could have done it in 1992 or even 1991. But they did not.