Nicola Sturgeon accepted an invitation to meet a member of President Obama’s national security team.
It is understood they spoke about defence and foreign affairs issues including the renewal of Trident, which the SNP opposes.
They also discussed the UK’s membership of the European Union.
The Scottish and US governments are both strongly in favour of the UK remaining a member of the EU, with a referendum on the issue due to be held next year.
The meeting between Ms Sturgeon and the US official followed an earlier discussion between the first minister and the US Deputy Secretary of State, Tony Blinken.
It had been the highest level meeting any Scottish government minister has had in Washington for six years.
US officials have said they were recognising the SNP’s new status as the third largest political party in the UK.
Ms Sturgeon, who has been on a four-day trip to the US, also met Christine Lagarde, the head of the International Monetary Fund (IMF), in Washington.
The first minister urged Ms Lagarde to help increase the number of women at all levels of business, and discussed the state of Scotland’s economy.
She also addressed the Council on Foreign Relations think tank in Washington, where she said the UK may not continue in its current form if the government at Westminster fails to adapt to the changing political landscape.