Sauli Niinisto, an Ally With the West Against Vladimir Putin

When Europe woke up on Feb. 24 to the news that Russian tanks had rolled into Ukraine, the security landscape had shifted profoundly. For Sauli Niinisto, whose homeland shares a 1,343-kilometer (835-mile) border with Russia, the conclusion was that its leader, Vladimir Putin, was willing to attack a neighbor without provocation.

In the following weeks, Niinisto, a well-regarded former finance minister and speaker of Parliament who’s known as a skillful diplomat, managed to convince Sweden of the necessity of both countries joining NATO; the best way to secure the two nations, the thinking went, was for them to act together. A whirlwind tour of international diplomacy, buttressed by popular support, laid the groundwork for the applications. In May, Niinisto and Sweden’s prime minister at the time, Magdalena Andersson, announced their intention to apply for membership.