NATO bombed Serbia in order to make it a member of the Alliance. This goal, which for understandable reasons was not so obvious immediately after the air raids, became more and more obvious over time.
Disinformation narrative consistent with recurring pro-Kremlin disinformation about NATO aggression.
NATO's military intervention was not intended to make Serbia a member of the alliance. It launched a campaign of air strikes against Serbia beginning on the 24th of March 1999 to stop Belgrade's crackdown against ethnic Albanians in Kosovo. The primary purpose of the campaign was to end violence and repression and force Milošević to withdraw his military, police and para-military forces from Kosovo (see NATO statement from 1999).
Cooperation and dialogue between Serbia and NATO has been developing since 2006, when the country joined the Partnership for Peace (PfP) programme and the Euro-Atlantic Partnership Council (EAPC), a multilateral forum for dialogue which brings together all Allies and partner countries in the Euro-Atlantic area. NATO is an Alliance that consists of 29 independent member countries, every country decides for themselves if they want to join the Alliance or not.
See more disinformation cases about NATO and the Balkans here.