Until this week, travelers have been able to enter Sweden freely by train, car and ferry across the Danish border.
Now they will have to disembark and show their driver's license or passport before being allowed to continue their journey. Anyone without a valid form of ID will be turned back.
The new policy caused some delays early Monday, particularly for commuters who live in Sweden and work in neighboring Denmark -- nearly 75,000 people a day cross the Oresund bridge between the two countries -- but fears of traffic chaos and a backlog of refugees did not materialize.
Sweden had in excess of 160,000 asylum application in 2015, more than double the previous year. As the flow reached its peak, some 10,000 refugees were coming into the country each day.
In December, the Swedish government declared that the large number of refugee arrivals were "a serious threat to public order and domestic security," forcing it to introduce new legislation allowing ID checks at its borders, among other measures. The legislation is temporary and valid for three years.
The number of refugees arriving in Europe has dropped dramatically since December, due to stricter border policies in Turkey and other EU nations, as well as worsening weather conditions along the refugee route.
In Germany, the destination of choice for many refugees, numbers have dipped to roughly 3,000 asylum seekers a day, according to Germany's Federal Police; even fewer are making their way north to Denmark and Sweden.
Sweden's new policy prompted Denmark's Prime Minister, Lars Løkke Rasmussen, to announce Monday
that his country would impose random ID checks at its border with Germany for the next 10 days, with the possibility of extending the controls for another 20 days.
In response, Germany's foreign ministry spokesman, Martin Schaefer, told reporters that the refugee crisis was putting Europe's border-free Schengen area "in danger."
Sweden is the latest EU country to install stronger border controls in response to the refugee crisis. Germany, Austria and France
have all imposed some form of identity checks at their borders in recent months.
Sweden and Germany have taken in the vast majority of refugees to the EU so far; both countries are struggling to house and care for hundreds of thousands of new arrivals. They have appealed for a joint EU policy that would share the distribution of refugees across more states.