Swedish authorities launched military exercise Aurora 23 on Monday, starting weeks of drills "in the air, on ground and at sea," according to a statement from the Swedish Armed Forces.

Aurora 23 is the biggest exercise in Sweden in more than 25 years, and will run until May 11.

Soldiers from the US, the UK, France, Germany and neighboring Nordic nations are all taking part in the drills. The exercise aims to train the troops for the event of a major armed attack on Sweden.

"Together with military units from our partner countries we build security and, concurrently, reinforce the Swedish operational capability," the Swedish Armed Forces said in a statement.

"Uniformed personnel and land vehicles will circulate outside the bases and airports," the statement added.

Large parts of Sweden will be covered, but units will be mainly noticed in southern Sweden and the strategically important island of Gotland.

Sweden's bid to join NATO remains blocked

Last May Sweden and neighboring Finland announced bids to join the NATO alliance after decades of military non-alignment.

But while Finland became NATO's 31st member state in the beginning of April, Sweden still faces opposition from Turkey and Hungary.

NATO diplomats hope that Turkish President Recep Tayyip Erdogan will approve Sweden's membership if he is confirmed as the next head of state following the Turkish elections next month. 

vh/dj (AFP, dpa)