Estonia

Prime Minister Kaja Kallas has led the former Soviet republic since 2021. She's an outspoken critic of Russian President Vladimir Putin, and a vocal supporter of Ukraine.

U.S. troops are training in Estonia, just 70 miles from the Russian border. It points to NATO's increased activity in the Baltic states and Poland amid the growing tensions with Moscow.

It could be the next big spy movie: an Estonian intelligence agent nabbed by Russia on spy charges. Russia says he was spying on them; Estonia says he was kidnapped in a cross-border raid.

The Estonian capital is dotted with medieval towers and Soviet architecture that belie its status as one of the world's most technologically advanced cities. Residents use a smart card to ride the bus, and mail packages and pay for parking with their phones.