Britain remains a vital anchor to the success of Nato

We have obligations - to our own citizens as well as to our allies - which can't be met if our military dwindles

Since its success as a defensive bulwark against the Soviet Union during the Cold War, Nato has been carving out a new and more offensive role. The new strategy was evident first in Kosovo in 1999, then in Afghanistan, and most recently in the overthrow of the Gaddafi regime in Libya, a country now threatened by the advance of Isis, the latest menace to regional stability on Nato’s southern and eastern frontiers.

But Nato’s greatest priority has reverted to its original one: Russia. In an increasingly dangerous world, few places suddenly seem more dangerous than the alliance’s eastern backyard. Vladimir Putin’s regime casts an ominous shadow not just over Ukraine, but over the Baltic states of Estonia, Latvia and Lithuania, all Nato members to whose aid the alliance is treaty-bound to come in the event of foreign attack. At which point two questions arise. Would Nato have the will and capacity to meet that obligation? And where are we in all this?

Britain may be a middling power in a world whose economic balance is shifting from Europe to Asia. But in Nato it is nonetheless pivotal. The alliance may be American-led and American-dominated, but Britain remains a vital anchor. Not only are we a fellow nuclear power. We have been the staunchest and closest military ally of the US, in terms of intelligence sharing, battlefield operations and interoperable hardware.

That role, however, now seems at risk. Already UK defence spending has slipped perilously close to the 2 per cent share of GDP to which Nato members are committed, and forecasts suggest it will fall to just 1.7 per cent by 2020. And the country has an election on its mind, dominated by economic and constitutional issues and Britain’s relationship with Europe. Defence spending is rarely a vote winner, less so than ever perhaps in an atmosphere still poisoned by memories of the Iraq war, which in turn led the Commons to vote in 2013 against British air strikes in Syria to overthrow Bashar al-Assad. Yet polls suggest that voters are increasingly concerned about the decline of their country’s clout on the global stage.

That concern, however, pales beside the alarm felt in Washington. From President Obama down, US officials and military commanders have warned and pleaded with Britain not to cut our defences further. Yesterday, Samantha Power, Mr Obama’s ambassador to the United Nations, delivered a similar message in Brussels. The US fear is twofold – that further backsliding by Britain and other Nato members (all but three of whom have already fallen below the 2 per cent benchmark) will reduce the alliance to an embarrassing figleaf for American power, and prove that Europe now simply lacks the will to defend itself against a renewed challenge from Moscow.

To be sure, the Foreign Secretary, Philip Hammond, warned in London yesterday that Vladimir Putin’s Russia is potentially the “single greatest threat” to Britain’s security, and similar assurances of British resolve will be conveyed in Washington today by Michael Fallon, the Defence Secretary.

But words alone are not enough. For all the ringing language, Mr Hammond and the Chancellor, George Osborne, have refused to rule out future cuts in the defence budget, despite calls from both sides of the aisle in Westminster that military spending be ring-fenced.

Britain has been a country that for many years – thanks to our military prowess and willingness to use it (although not always advisedly) – has “punched above our weight in world affairs”, in the words of a former Foreign Secretary, Douglas Hurd. But, right now, it seems to have lost interest in punching at all – with consequences that could damage Nato and everything it stands for.