Women in Denmark who have turned 18 became eligible for military conscription on Tuesday, as the Nordic country moved to expand its armed forces to prepare for a possible threat from Russia and to meet American expectations of NATO members.

The agreement to start including women in the draft was announced in March and passed by the Danish Parliament in June. “The defense needs all the fighting power we can mobilize,” Michael W. Hyldgaard, Denmark’s defense chief, said in a statement in March when the change was announced. “This requires that we recruit from all over society.”

Danish women have long been allowed to volunteer to serve in the military, but until now they were not entered into a lottery system for compulsory service like their male peers. The government uses the lottery only if there are not enough volunteers to fill its needs. Women currently make up about 10 percent of the Danish Army, Navy and Air Force.

As it braces for a more precarious future — in which Russia may menace Europe beyond Ukraine’s borders — Denmark has been pushing hard to find more soldiers. A nation of six million, it currently has about 16,600 uniformed employees in the military and emergency services.

Denmark announced in January that it would aggressively increase its military spending, and it has taken a more hawkish approach to defense since Russia’s full-scale invasion of Ukraine in 2022. While Denmark does not share a border with Russia, its leaders are wary of Russia’s presence in the Arctic and in the Baltic Sea, where there have been instances of sabotage on infrastructure.

“I don’t think Danish politicians are fearing Russian tanks in Copenhagen tomorrow or anything like that, but it’s tied to fears that Russia could be a problem,” said Mikkel Runge Olesen, a senior researcher at the Danish Institute for International Studies.