Germany’s government announced temporary border controls at all of the country’s land borders on Monday in what it called an attempt to tackle irregular migration and protect the public from threats such as Islamist extremism.

The controls will start on Sept. 16 and initially last for six months, the interior ministry said in a statement.

“We are strengthening internal security and continuing our hard line against irregular migration,” Interior Minister Nancy Faeser said.

Germany has hardened its stance on migration in recent years, as the government scrambles to retake the initiative after support for the far-right Alternative for Germany (AfD) has surged over the issue.

Recent deadly knife attacks in which the suspects were asylum seekers have stoked concerns over immigration. The Islamic State group claimed responsibility for a knife attack in the western city of Solingen that killed three people in August.

The AfD earlier this month became the first far-right party since World War Two to win a state election, in Thuringia.

The announcement comes just two weeks ahead of an election in Brandenburg where Chancellor Olaf Scholz and Faeser’s centre-left Social Democrats (SPD) are fighting to retain control of the government.

The imposition of temporary border controls could be another test of European unity.

Germany shares its more than 3,700-km-long (2,300 miles) land border with Denmark, the Netherlands, Belgium, Luxembourg, France, Switzerland, Austria, the Czech Republic and Poland.

Austria’s Interior Minister Gerhard Karner told Bild newspaper on Monday that his country would not take in any migrants turned away by Germany at the border.

“There’s no room for manoeuvre there,” he said.

“It’s the law. I have directed the head of the federal police to not allow any returns,” he added.

Germany last year announced stricter controls on its land borders with Poland, the Czech Republic and Switzerland in response to a sharp increase in first-time asylum requests.