By hoisting its flag outside the UN building on 22 May 1992, with then Croatian President Franjo Tudjman and UN Secretary-General Boutros Boutros-Ghali attending, Croatia was admitted to the organisation together with Slovenia and Bosnia and Herzegovina.
"The UN membership rounded off Croatia's international legitimacy," Plenkovic said at the ceremony attended by state, military, police and church leaders and representatives of the diplomatic corps.
UN membership was achieved only months after 12 European Community member states recognised Croatia and a month after the US did so, and Croatia's first diplomatic successes were achieved in the UN, Plenkovic said.
"Then we were a recipient of security. Several UN missions were on our territory and, by all analyses, the most important and most successful one on European soil since its establishment was the mission for the transitional administration in eastern Slavonia, Baranja and Srijem," he said, adding that "the peaceful reintegration was a success both for Croatia and for the UN, as well as a model for similar situations elsewhere in the world."
"We have shared that experience of ours with our friends in Ukraine, who have a similar situation," Plenkovic said, adding that today Croatia provided and contributed to security around the world.
The UN remains to be a very relevant global organisation to which Croatia, in 25 years of membership, has been continuously contributing in all segments, but it has "a small specific quality which is imperfect in numerous aspects," namely that its leadership and key decision making mechanism still reflect the world at the end of World War II, Plenkovic said.
That's why there is no doubt that discussions on a reform of the Security Council, on the organisation itself and on decision making will remain on the agenda for many more years, he added.
President Kolinda Grabar-Kitarovic said Croatia's UN accession "was the crown of our independence" in which the UN played a key role. "At that time, Croatia's diplomacy was a second front-line because we had to fight for the recognition of the fact that the occupied areas of Croatia were an integral part of it, which was repeated in one Security Council resolution after another, which cemented Croatia's territorial integrity."
Today Croatia contributes to the solving many problems in the world and, aside from its experience in the liberation of territory, it also has experience in reconciliation, and it is in this area that "Croatia can find its own special niche" for action within the UN, the president said.
She recalled that Croatia was twice a member of the UN Economic and Social Council, that it was a member of the Security Council in 2008 and 2009, and that it vice chaired the Peacebuilding Commission in 2006. She announced Croatia would run for new posts in the organisation.
Grabar-Kitarovic mentioned Croatia's contributions to peace missions around the world, the first of which was in Sierra Leone in 1999. Currently, 17 Croatian troops are part of three peace missions - UNMOGIP in India and Pakistan, MINURSO in Western Sahara and UNIFIL in Lebanon.
Foreign Minister Davor Ivo Stier also addressed the ceremony. "The world we live in is far from perfect and humankind is exposed to increasingly big, complex and serious turmoil on a daily basis. In such conditions, stability and cooperation on a multilateral level are of key importance, and the UN represents the central forum and foundation of international relations in the survival of international law as well as the other numerous achievements of the past 72 years."
"Croatia attaches special attention to its membership of the Human Rights Council, which began this year and lasts until 2019," Stier said, adding that, with this membership, Croatia was rounding off its presence in nearly all UN bodies which, "given that we have been a member for only 25 years, is a fact we must be proud of."
He said it was up to the member states to find new solutions and ways of dealing with today's challenges, adding that many constructive criticisms over the past ten years had already led to reforms within the UN.