From nuclear to Nato, an independent Scotland would have several policy ramifications, but the official US reaction seems to be: no response at all

“Scotland’s what?” said the Department of Defense switchboard operator in apparent confusion. Scotland is voting on independence, the Guardian told her. “Oh.” A brief silence. “Wow.”

The buzz in Washington about Scotland’s proposed independence from the United Kingdom, even as a shock new poll this weekend showed the Yes campaign ahead 51% to 49%, is that there is practically no buzz in Washington.

But if Scotland votes for independence from the United Kingdom on 18 September it will have serious policy ramifications for the United States. First among these is the fate of the 58 Trident II D5 missiles leased from the US by the British government that have served as the UK’s primary deterrent against nuclear attack since 1990, and the four Vanguard-class submarines which carry them. There are other important questions too, ones about maintaining the balance of power in Nato; the relationship between the UK and the European Union, which could be jeopardised; and the larger foreign policy effect of a weakened United Kingdom.

Nonetheless, when asked for comment in July, the US official reaction was, essentially, no response at all. Lt Vanessa Hillman, a spokesperson for the Department of Defense (DoD), told the Guardian that this was “not something the DoD would take queries on”, and referred questions to the State Department. The State Department, getting a little testy – the Guardian asked the same question three times over the course of a week – said: “We don’t have anything on this at this point.”

The White House, when asked about contingency plans, referred to President Obama’s remarks at the G7 summit in Brussels in June, when he commented that the United Kingdom worked “pretty well, and we obviously have a deep interest in making sure that one of the closest allies that we will ever have remains strong, robust, united and effective partner.” When pressed further, the White House said: “We’re not going to comment beyond the president’s remarks. Thanks!”

“Washington as a whole is not generally aware that there’s even a referendum,” said James Acton, a senior associate in the nuclear policy program at the Washington DC-based Carnegie Endowment. “Most of the people who are dimly aware of it are assuming that the better together camp is going to win. I think there’s not been much deep thinking here about the ramifications of Scottish independence.”

Ian Wallace, a visiting fellow at the Brookings Institution, believes the stand-offish unwillingness of US institutions to comment is a strategic position. “[There is] an awareness that anything that might be seen as US interference into a Scottish decision would probably be counter-productive. There’s a desire to keep from doing anything that would undermine the case for keeping Britain together.”

But there are several facets of Scottish independence that could cause headaches for the US.

Acton, whose background is in nuclear physics, said that DC’s “nuclear community” was worried about what might happen to Trident, which Alex Salmond, the current First Minister of Scotland and the chief campaigner for independence, has pledged to kick out of their current base on the west coast of Scotland. There is some worry in US nuclear policy circles that Scottish independence could lead to the UK abandoning its nuclear program altogether. America very much doesn’t want that, said Acton. “The US is quietly very keen for the UK to remain a nuclear weapon state. They do not want to be the sole nuclear power in Nato.” (While France is a nuclear weapon state and an otherwise full member of the Nato command structure, it does not contribute use of its nuclear weapons to the alliance and does not attend meetings of the Nuclear Planning Group.)

The missiles that form the UK’s nuclear deterrent are leased from the American Atlantic Squadron pool, which is based at the US naval base at King’s Bay, on the Georgia coast, where America houses its own Trident submarines.

Acton thinks there is a possibility that the warheads, and possibly even the submarines, might have to be stored back at King’s Bay – at least temporarily – if an independent Scotland goes through with the Scottish National Party’s stated policy of ejecting them. “I think it would be an interim solution,” he said, “but might end up becoming permanent.”

“The bottom line – from our point of view – is that the Scottish government position is that it wants the fastest safe removal of Trident submarines,” said Stuart McDonald, a senior researcher for the Yes to Independence campaign.

Acton said that one way the situation could play out would be for pressure to be applied – including by the US government – using the possibility of Scottish membership in Nato as a bargaining chip to make the Scots agree to a long-term lease on the Trident base. McDonald, however, believes this is unlikely. “To say that there is a strong opposition to nuclear weapons in Scotland,” he added, “is understating the case.”

Franklin Miller, a former senior US defence official who spent 31 years working at the DoD, the Department of State and the White House, told the Guardian that the consequences for Nato would be grave. “The SNP position, that it will force the UK out of Faslane, thereby putting in peril the very existence of the UK [nuclear] deterrent, undercuts a key provision of the alliance, which is based on the nuclear guarantee provided by the US and the UK. If an independent Scotland were to knock out one of those two legs, it would cut to the heart of that doctrine, and isolate the US as the only nuclear provider for Nato,” he said. “Not a good thing.”

The Scottish National Party voted two years ago that an independent Scotland would apply to join Nato, but the issue of Scotland’s membership is deeply in doubt. “Would an independent Scotland be another free rider on US security guarantees?” Dr Tim Oliver, of the Center for Transatlantic Relations, asked. “The US is frustrated enough already at the number of bonsai armies in Europe. There wouldn’t be much expectation that Scotland could do anything in Nato.”

Oliver also said he thought there was an issue of international trust at stake. “The US fought one of the bloodiest wars in their history to hold its union together,” he said. “They can’t take the UK seriously if they just let their union fade.”