Michael Fallon, the U.K. Secretary of State for Defense, visits Washington this week, where he might be forgiven for using what Gore Vidal once called "the four most beautiful words in our common language: I told you so." Fallon's visit last March took place amidst media reports that the "special relationship" no longer seemed so special. U.S. officials and military officers were voicing concern over the cumulative effect of cuts in the British military following the David Cameron government's first, largely budget-driven "Strategic Defense and Security Review" (SDSR) in 2010. Speculation was rife that more trimming was on the way, even if Cameron's Conservative Party were to win the May elections. In addition, some saw the British as increasingly reluctant to pull their traditional weight in overseas military operations, especially in the Middle East. But Fallon was adamant: the United Kingdom, he told a Washington think-tank audience, has capabilities and political will that few countries can match, and it was not planning deeper defense cuts or "lowering its guard."

His confidence, it turns out, was justified.

Released on November 23, the 2015 SDSR promises a healthy boost for Britain's conventional military forces, including: three additional squadrons of combat aircraft (Typhoons and F-35 Lightings); nine new P-8 Maritime Patrol Aircraft (replacing the Nimrods eliminated by the 2010 SDSR); 20 Protector armed remotely piloted aircraft ("drones"); two rapidly deployable "Strike Brigades" equipped with new armored vehicles and upgraded Apache attack helicopters; and five new naval ships (for off-shore patrolling and logistical support). New and/or upgraded enablers—ranging from air-to-air refueling and transport aircraft to advanced equipment for Special Forces—are on order, and some £1.9 billion ($2.9 billion) over the next five years will be invested in defensive and "advanced offensive" cyber capabilities. Overall planned spending on equipment and equipment support over the next decade will total £178 billion ($269 billion), a £12 billion increase over the previous target. And the SDSR commits the government to "meet the NATO pledge to spend 2% of our GDP on defense...(and) guarantee a real increase in the defense budget in every year of this Parliament"—a politically significant promise that Fallon hinted at, but could not make before the May election.

True, this review likely will not satisfy everyone in the U.K and U.S. defense communities. For some experts, the British Army's planned end-strength of 82,000 active duty soldiers might be too small for the diverse and unpredictable security environment evident in Europe, the Middle East, and Africa. On the other hand, further cuts to the Army's ranks have been ruled out, and those of the Royal Navy and Air Force will receive modest increases.

Regarding nuclear weapons issues, the SDSR reaffirms the government's position that a four ballistic missile submarine (SSBN) fleet is necessary to maintain at least one on operational patrol at all times, a posture known as "Continuous at Sea Deterrence." However, the review mentions two new factors that, at first glance, might concern those (especially in Washington and Paris, as well as in London) who have fretted over the commitment of successive British governments to renew the UK nuclear deterrent, composed of four aging Vanguard-class SSBNs (which carry U.S.-built Trident missiles), with a "like-for-like" fleet of four new "Successor" boats.

First, according to the SDSR, the estimated manufacturing cost of the four Successors likely will total £31 ($47 billion), including anticipated inflation over the 20-year program. This represents a significant increase -- even when accounting for inflation -- over the estimated total cost of £11-14 billion ($17-21 billion) at 2006 prices contained in the government's December 2014 Successor update report to Parliament. Second, the entry-into-service of the first Successor has moved to the "early 2030s," a noticeable slip from the "late 2020s" timeframe also specified to Parliament just one year ago. And this slip is not the first: a defense ministry report to Parliament in 2006 indicated that the first Vanguard would be leaving service "around 2022," implying that the first Successor would be entering service the same year.

Neither the cost nor schedule revision should be too surprising, given the scale and technological complexity of the Successor program. Indeed, the separate program to build seven Astute-class attack submarines for the Royal Navy is behind schedule and over cost, and some experts see advantages to finishing their construction before the shipyards start on the Successor, which is said to incorporate new nuclear propulsion and hull design concepts. Still, by the early 2020s, the Vanguard-class SSBNs will reach their original 25-year design life, and ongoing life-extension programs are lengthy, expensive, and not risk-free. Hence, as recently as October, Fallon put British submarine industry leaders publicly on notice that "there can be . . . no failure to meet [Successor] build times . . . no overrunning costs . . . no excuses."

Given the SDSR's revisions, Fallon's warning will no doubt be used by staunch opponents of the nuclear deterrent—including Labor Party leader Jeremy Corbyn and the Scottish Nationalist Party – to indict the government's credibility when it brings the renewal program before Parliament, probably in mid-2016. The current Conservative majority in the House of Commons ensures approval of the next big step on Successor acquisition. But backers of the deterrent could face new challenges in the following years if more gaps arise between policies, promises, and performance.

One nightmare scenario: the British vote for quitting the European Union (popularly known as "Brexit") in the referendum promised by Cameron by the end of 2017. This would prompt the pro-EU Scottish Nationalists to call a second referendum on independence for Scotland, which they would be better positioned to win than their failed attempt in September 2014. And if they do win, the Nationalists then would move to terminate arrangements, dating from the 1960s, for basing the U.K. SSBNs and their nuclear warheads on the Scottish west coast. Don't be shocked if they quote Gore Vidal, too.

Leo Michel is a non-resident senior fellow, Brent Scowcroft Center on International Security, Atlantic Council, where this article first appeared.

Image: Flickr/Defence Images