In 2018, over a hundred localities in Moldova and dozens in Romania issued symbolic declarations of unification (Romanian: declarații de unire, sg.: declarație de unire) with the other country. Such declarations were also issued by some Moldovan districts and Romanian counties (which are respectively each country's first-level administrative divisions), members of the Moldovan and Romanian diasporas and other non-territorial entities.
A movement for the unification of Moldova and Romania exists in both countries. Both share a common Romanian language, an Eastern Orthodox faith and strong cultural and historical connections. Supporters of the movement look back on the union of Bessarabia with Romania on 27 March 1918, Bessarabia being a region corresponding up to a point with modern Moldova. As the regions of Bukovina and Transylvania also united with Romania in 1918, with the three unifications being collectively known as the Great Union (Romanian: Marea Unire) among Romanians, 2018 was a symbolic year for unionists and nationalists, celebrated as the centenary of the Great Union.
The Moldovan commune of Parcova was the first to declare unification with Romania on 23 January. It was followed by over a hundred localities in Moldova, including the towns of Cimișlia, Edineț and Ungheni, but also several districts the first of which was Strășeni District. As a response, the Romanian commune of Parva declared unification with Moldova on 19 February, being followed by dozens of localities including major cities like Iași, Constanța, Brașov, Craiova and the capital Bucharest, as well as several counties the first of which was Prahova County. Members of the Moldovan and Romanian diasporas issued unification declarations in Belgium, Canada, France, Greece, Ireland, Italy, Portugal and the United Kingdom, and even in the European Parliament; so did Moldovan and Romanian students and teachers, primary schools and high schools, universities, monasteries and parishes, unionist associations and individuals and Transnistria War veterans and signatories of the Moldovan Declaration of Independence, among several others. Ialoveni District and Băcioi in Moldova declared unification respectively with Ilfov County and Aleșd in Romania, while Iași also declared unification with Bukovina, the northern half of which is today in Ukraine.
The declarations were not meant to carry legal weight, but their strong symbolic value elicited reactions in both Moldova and Romania. They received a negative response from the President of Moldova at the time, Igor Dodon, and the Party of Socialists of the Republic of Moldova (PSRM), to which Dodon had belonged before his election. Dodon defined the declarations as a threat to Moldovan statehood and sought the prosecution of local officials who signed them. Dodon and the PSRM launched a campaign for Moldovan localities to issue declarations against unification with Romania, reaching a number of over three hundred localities according to the PSRM, including the second-largest Moldovan city of Bălți and towns such as Soroca, Comrat and Sîngerei, as well as Ocnița District. In some localities, separate declarations in favor and against unification were issued at different times by local officials. In Romania, the Parliament adopted a declaration expressing the legitimacy of the desire of Moldovans in favor of uniting with Romania and Romania's preparation to respond to any moves towards unification by the population of Moldova.