Sweden received assurances from the US that it would receive support during the period when a potential application to join Nato will be processed by the 30 nations in the alliance, foreign minister Ann Linde said in Washington on Wednesday.
Sweden and neighbour Finland stayed out of Nato during the cold war, but Russia annexated Crimea in 2014 and invaded Ukraine have led the countries to reconsider their security policies, with Nato membership looking increasingly likely to be a reality.
Both countries are concerned that they would be vulnerable during an application process, which could take up to a year to be approved by all Nato members.
Linde told Swedish TV from Washington after meeting US secretary of state Antony Blinken that they were not going to go into any details.
She said that there were not concrete security guarantees, which you can only get if you are a full member of Nato.
Linde didn't say what assurances she had received from Blinken.
They would mean that Russia could be clear that if they had threatened Sweden with any negative activities, it would not be something that the US would allow to happen without a response, she said.
Sweden's defence minister last month said that an application could trigger a number of responses from Russia, including cyber-attacks and hybrid measures like propaganda campaigns to undermine Sweden s security.
Moscow has warned that it could deploy nuclear weapons and hypersonic missiles in the European exclave of Kaliningrad if Sweden and Finland become Nato members.
Linde, who will travel to Canada to discuss security matters with its government, said that the US strongly supports Swedish and Finnish membership in Nato, which would increase stability in the Baltic and Arctic regions.
Sweden and Finland are expected to make a decision on whether to join Nato this month.