Sweden became the 32nd member of NATO on 7 March 2024 — option 1.

The two hundred years of neutrality. Sweden had stayed out of military alliances since 1814, the end of its brief campaign against Norway, and remained non-aligned through both World Wars and the whole of the Cold War — a policy of roughly two centuries, which is exactly what the question’s phrase points to. Russia’s full-scale invasion of Ukraine in February 2022 overturned that policy, and Sweden applied for membership together with Finland in May 2022.

Why it took nearly two years. Accession requires ratification by every existing member. Turkey withheld its consent over Sweden’s handling of Kurdish groups it regards as terrorist organisations and over arms-export restrictions, ratifying only in January 2024; Hungary was the last to ratify, in February 2024. Sweden formally deposited its instrument of accession in Washington on 7 March 2024.

Why Finland is the sharpest distractor. The two Nordic countries applied together and are constantly mentioned in the same breath, but Finland’s accession was completed a year earlier, in April 2023, and Finland’s non-alignment dated from after the Second World War rather than from 1814. The phrase “almost 200 years” therefore fits only Sweden.

The strategic effect. With both Nordic states inside the alliance, the Baltic Sea is now ringed by NATO members except for Russia’s own coast at St Petersburg and Kaliningrad, and the Swedish island of Gotland becomes a key position in the alliance’s northern defence.

Hence, the answer is Sweden.