As my colleague Doug Bandow noted on Cato@Liberty a few days ago, Scottish independence is for the voters of Scotland to decide. And so it should be. But, as I write over at Foreign Policy, U.S. policymakers need to be aware that Scottish independence would carry some key costs for the United States:

1. The loss of nuclear submarine basing privileges is the most concrete cost of Scottish independence, with Scotland’s nationalist party pledging a ‘nuclear‐​free’ Scotland if a Yes vote occurs. U.S. nuclear submarines, though based in King’s Bay, Georgia, use the United Kingdom’s HMNB Clyde Naval Base at Faslane, Scotland for maintenance and deployment needs. The site is located conveniently close to key North Sea patrol waters, and has acted as a visiting port for U.S. submarines since the Cold War. The loss of the base will force the UK to relocate its four Trident submarines, and the paucity of available sites in Europe may eventually lead to UK submarines being based alongside their American counterparts in Georgia.
2. The UK and United States also have strong, historical links in intelligence sharing and military cooperation, formalized in the 1946 UKUSA agreement. Intelligence sharing and operational burdens are widely shared; officers on both sides of the Atlantic even refer to each other as ‘cousins.’ But independence could undermine the value of this alliance for the United States, at least in the short term. In the case of a Yes vote, the remainder of the United Kingdom (RUK) will need to rebuild its military and intelligence capabilities, extricating itself from Scotland, and negotiating which military assets will go to which country. During this period, the United States will lose the benefit of British intelligence and military support.
3. The breakdown of the UK will also result in the loss of a valuable U.S. supporter on the world stage. The UK is often the only nation which commits substantial levels of troops or financing to joint military or humanitarian operations. While ‘partner states’ like France committed only 88 troops to the War in Afghanistan, the UK contributed 10–15% of total troops to the conflict. In Iraq, the UK was responsible for almost half of the non-U.S. troops involved. The UK also carries its own weight in NATO, contributing between 2.5–3% of GDP in military spending each year, a level few European states achieve. The loss of Scotland will carve up the UK, removing at least 8% of its population and tax base, making it less able to commit to any U.S. initiatives.

The timing could not be worse: achieving consensus on Syria, Ukraine or a host of other issues will be harder in the turmoil of a Yes vote for independence. Whether the United States should be involved in these conflicts is debatable at best, but they will be costly, especially if Britain can’t contribute. An independent Scotland, even without the incipient startup costs of independence, is not going to fill that gap. U.S. policymakers shouldn’t be telling Scotland what to do. But they should be worried. If a Yes vote occurs, the costs will certainly impact the United States