A senior official in the White House National Security Council (NSC) has been warned of the "detrimental" implications of an independent Scotland.
Professor Azeem Ibrahim, a former Biden campaign adviser and foreign policy expert, also warned of a "deficiency of understanding in Washington" of what Scottish independence would mean for the NATO alliance.
The warning was reportedly sent in an email by Prof Ibrahim to a senior NSC official saying it is "imperative that the administration be made aware of this threat".
Scottish First Minister Nicola Sturgeon speaks at the Scottish National Party (SNP) manifesto launch, in Greenock, Scotland.
RUSSELL CHEYNE
In an article published yesterday in The National Interest, Prof Ibrahim warned: "In becoming independent, Scotland would paralyze the nuclear defensive stance of the UK for at least five to ten years, blowing a huge hole into NATO’s defensive posture at a time when the alliance is tested unlike any since the end of the Cold War.
"The entire nuclear submarine infrastructure that the UK relies on is based in Scotland, and the SNP has pledged to close it down upon independence.
"Relocating the infrastructure is going to be hugely expensive, and more importantly, it will take a long time."
Prof Ibrahim went on to argue that now is "the worst possible time for delivering Scottish independence".
He continued: "It is economically and politically inauspicious and would make Scots poorer and the entire Western Alliance less safe.
Scotland's First Minister and Scottish National Party (SNP) leader Nicola Sturgeon gestures outside a polling station during the local elections in Glasgow, Scotland.
RUSSELL CHEYNE
"Nicola Sturgeon knows what she wants. We must know that too—and be on guard lest we unconsciously aid her breaking up of the United Kingdom, and the weakening of treaty allies as we all face a newly dangerous and uncertain world."
In addition to sending copies of his article in National Interest, Express.co.uk reports that Prof Ibrahim noted to the senior NSC official: "The First Minister of Scotland, Nicola Sturgeon will be visiting Washington DC tomorrow where she will be speaking at the Brookings Institute and meeting various officials.
"Nicola Sturgeon is the leader of the Scottish National Party which exists only to break up the United Kingdom and make Scotland an independent country.
"There is a deficiency of understanding in Washington of the strategic implications of Scottish independence and its highly detrimental effect on the national security of the United States and NATO.
"I have penned the attached essays in Foreign Policy Magazine and National Interest highlighting the nature of these threats which are now much more pronounced with events in Europe.
"It is imperative that the administration be made aware of this threat and would therefore deeply appreciate if you could circulate my articles in your daily security briefing to relevant government departments."
Prof Ibrahim told Express.co.uk: "The security situation in Europe has changed dramatically over the last few months with even neutral Sweden and Finland scrambling to join NATO.
"The Prime Minister was correct in confirming that the UK will aid both nations in the eventuality of an attack by Putin."
He went on: "This is to ensure that they are protected by the UK’s nuclear umbrella whilst their NATO memberships are considered by member nations.
"The UK’s nuclear umbrella has never been more critical to European defence."