Another week, another call for the UK to provide more clarity on the terms of its departure from the EU – this time from Jean-Claude Juncker, the president of the European Commission. While Brexit requires ministers to focus on the detail, the shocking chemical attack on UK soil, with alleged Russian involvement, serves as a grim reminder of the serious consequences that bigger-picture politics can have on this country.

Given the gravity of the situation, there are plenty of voices calling for a robust response. Former national security adviser Lord Ricketts has said the task is now to “punish Russia in a way that will make Vladimir Putin sit up and take notice”. Indeed, the Foreign Secretary has made headlines for seeming not to rule out cyber attacks in retaliation. Jeremy Corbyn, meanwhile, has been criticised for calling for dialogue with Russia.

Dialogue should always be an option. The Foreign Secretary visited Russia last year despite growing concern over Russian interference in foreign elections. But it is hard to imagine productive exchanges at present. The Organisation for the Prohibition of Chemical Weapons may help uncover the source of the nerve agent, though more broadly, robust United Nations action is probably off the table given two of the five Security Council permanent members (P5) are involved.

But diplomacy will inevitably form the core of the UK’s response. In the coming days and weeks, the UK will need to work with allies: as Ricketts has noted, any action “will be much more effective if there can be a broader, NATO-EU solidarity behind us”. In the longer term, the UK must work to shore up international support at a time when questions are being raised about its influence on the world stage.

Last year, the UK suffered a number of diplomatic setbacks at the UN, including the loss – for the first time in 70 years – of a British judge on the International Court of Justice, and defeat in the General Assembly over the Chagos Islands. While a number of factors influenced these decisions, not least pushback from the wider UN membership against the privilege of the P5, it was telling that the French candidate was able to prevail on the first occasion, and that the UK was not able to muster the support of its EU allies on the latter.

These incidents might seem like small fry when set against the attack in Salisbury last week. But they matter because they are being framed as part of a broader narrative of British decline. Rightly or wrongly, there is a perception that the UK’s influence is waning and that is now a country more interested in trade deals than in the business of multilateral diplomacy, which is, of course, crucial to the success of those deals. This narrative is being spun by UK allies and adversaries, and it is self-perpetuating, especially as it is echoed by some within the country. With apologies to Mark Twain, reports of the UK’s demise may be exaggerated but they are growing louder.

As hard power shifts and states – especially those whose power is on the wane – deploy asymmetric acts of aggression, the levers of soft power and alliances are all the more important. The UN, in which the UK continues to have outsize influence, is the obvious forum to cultivate both, as UNA-UK argued in its recent evidence on the National Security Strategy.

This will require demonstrating that the UK can still play an important global role (and resourcing the FCO to do it) in finding solutions to crises and driving forward positive initiatives. There is no shortage of policy options here, from securing a substantive Security Council resolution on the appalling humanitarian situation in Yemen, to leading by example by suspending arms sales to Saudi Arabia, which have exacerbated that very situation, to pushing for further action to tackle sexual exploitation and abuse.

It will also require a reframing of the UK’s global position, and a proper national conversation about what type of country we want to be. With so many other challenges, this might seem pretty low down the to-do list. But how a country sees itself matters. The aftermath of the EU referendum has shown just how divergent views are. Global instability too has its roots in the growing disconnect between people and politicians.

Since 1962, when the US Secretary of State Dean Acheson commented that Britain had lost an empire but not yet found a role, the UK has wavered between emphasising its colonial history and hard power, and its self-characterisation as a small island that punches above its weight. The current ‘Global Britain’ label appears to be the latest expression of this balancing act. On the one hand, it recognises the changing global power landscape and calls on others to step up and take responsibility for tackling shared challenges. On the other hand, some of the rhetoric on expanding ‘UK plc’ in the Commonwealth has been interpreted as Empire 2.0.

There is now a real opportunity to set out a vision based on the future – one that recognises that exceptionalism is no longer an option and that British power comes in large part from what it brings to the table. The International Development Secretary’s description of the UK as a “development superpower” is a step in the right direction. We have long thought of ourselves as a diplomatic superpower; to many this now sounds like an idle boast.

Britain is no longer a big power, in fact the era of big powers may be over. Denial will only accelerate the UK’s decline. But a United Kingdom committed to multilateralism and building, through principled policies, the trust of a broad and diverse network of allies old and new, could yet earn and therefore retain its privileged position at the centre of global diplomacy.