Siim Sikkut, a government policy adviser in charge of the new e-citizen effort, believes that the number of virtual citizens of Estonia could top 10 million by 2025—a huge increase over the country’s current population of roughly 1.3 million.

Here’s why virtual countries, and digital citizens, matter to U.S. security: A country with an increasingly antagonistic relationship with Russia is about to expand its cyber profile by a factor of more than seven, and it will be looking to the United States for protection.

At least, that’s what history suggests. In 2007, Estonia was the victim of one of the most famous coordinated cyber attacks in history following a dispute about the placement of a controversial World War II memorial. It was a small spat over a bronze statue dedicated to the Red Army soldiers who fought to liberate Tallinn from German control. But it was also an argument with big consequences.

Russian-aligned hackers, which many believed were acting under orders from the Kremlin, launched distributed denial of service or DDOS attacks affecting government and media outlets. The impact, for a country that’s highly reliant on the Internet, was surprising.

As The Economist described it in 2007: “Even at their crudest, the assaults broke new ground. For the first time, a state faced a frontal, anonymous attack that swamped the websites of banks, ministries, newspapers and broadcasters; that hobbled Estonia’s efforts to make its case abroad.”

Very quickly, a country that was a pioneer in providing e-services to its people became a cautionary tale not to mess with Russia. Estonia’s government responded quickly.

“In cyber security, Estonia learned hard lessons” from the 2007 attack, said Michael Polt, former U.S. ambassador to Estonia. Since then, according to Polt, the country has set a much higher standard of cyber security, and has advocated that its friends and allies, especially in NATO, do the same. "Estonia is better prepared for and more aware of cyber threats than most counties,” Polt said.

Other experts agreed. Robert Lenz, former deputy assistant secretary of defense for cyber, identity, and information assurance and current president of the firm Cyber Security Strategies, called Estonia a recognized leader in cyber security.

Today, Estonia allocates 40 million euros (roughly $50 million) to cyber security every year, which amounts to about .5 percent of the country’s overall annual spending. But being a leader in cyber security doesn’t fully inure a country to cyber attacks or cyber warfare. More online activity means more targets and potential vulnerabilities. That matters to the United States, which played a big role in Estonia’s response to the 2007 assault. U.S. forces in Europe provided personnel and technical assistance, and Estonia eventually became a hub for cyber collaboration, Lenz said.