The safety of the people is the highest law, said Cicero. He was right. And it is a core duty of the British government to deal effectively with a nerve gas attack on our streets, which has seriously incapacitated three people and endangered many more. Theresa May has risen to the challenge. The authorities have swiftly identified the poison used in the attack on Sergei and Yulia Skripal as Russian. We have demanded that Russia explain what has happened, or face consequences. It is already clear that we can expect obfuscation. We will then have to deliver the prime minister’s “vigorous” response.

I was British ambassador in 2006 when Alexander Litvinenko was poisoned in Moscow. The similarities are striking: almost certain Russian guilt, a nasty poison deployed on British streets, Russian refusal to cooperate. We introduced sanctions – diplomatic expulsions and limits on links with the Russian intelligence agencies – intended to deter any recurrence.

We should make life for Russian security agencies in the UK as difficult as possible

With hindsight, those sanctions were not enough. We should be tougher this time. Three baskets of measures are on the table. First, the “diplomatic”. The Russian security agencies almost certainly carried out the Salisbury attack. We should build on the Litvinenko measures to make life for them in the UK as difficult as possible. We should freeze our contacts with them and rigorously curtail their travel from Moscow. A significant proportion of those working in the Russian embassy should be expelled (with sad consequences for my innocent diplomatic colleagues and friends in the British embassy in Moscow who will inevitably bear the brunt of Russian retaliation).

Second, economic measures. There is far too much crooked money floating around London. This is not only a Russian problem and we have tough new tools (such as “unexplained wealth orders”) to tackle it. These tools should now be energetically deployed. At the same time the government should accept the “Magnitsky clause”, which would impose sanctions on human rights violators.

Third, general contacts. Top of the list is this year’s Russia World Cup. I doubt there is a widespread desire for the England football team to withdraw, and in any case the history of sports boycotts is unimpressive. But plainly we will not want to send senior-level UK representatives, and the same will apply to representation at other major events hosted by the Russians.

The UK acting alone will not be enough, however. The apparent brazenness of the Skripal attack, using a poison Russia must have known would be linked to it, suggests it is almost deliberately courting UK hostility. We will need allied support to make an impact. Here the Litvinenko precedent is not encouraging. Our allies (particularly the Europeans) said the correct things but were unwilling to risk their links with Moscow in support of what they saw as a UK/Russia row.

The scene connected to the Sergei Skripal nerve agent attack in Salisbury, UK. Photograph: Jack Taylor/Getty Images

The politics this time are very different, of course. Russia could not be more mistrusted. And the fact that what happens in Salisbury today could happen in Avignon or Frankfurt tomorrow will have force. But it is still going to take a big effort to turn supportive words (which are coming in abundance) into real action. Meanwhile, the US, with its deep domestic divisions on Russia policy (as illustrated by Rex Tillerson’s departure as secretary of state today), is almost certainly out of the game.

So there is much to be done to assemble measures to deter any future Skripal-type attack. All our energies for now need to go into that. But we must not forget the longer term. When the heat eventually dies down, Russia will still be a major nuclear power crucial to tackling the full spectrum of international problems such as Syria, Iran, arms control, Islamist terrorism and cybersecurity. A big blunder following Russia’s 2014 intervention in Ukraine was to try to isolate Russia. It didn’t work. Key countries (China, India) never participated, and those that did quickly found themselves eating their words as the costs and dangers of being out of touch with Russia became apparent. The UK has been slow to acknowledge this lesson, but it would be a mistake, for example, to withdraw our ambassador from Moscow and cut off other key official links, further narrowing what is already a perilously thin line of communication.

More broadly, relations between Russia and the west are now at their most dangerous level for decades. Both Russia and the US are rebuilding their nuclear arsenals, and links between our militaries are almost non-existent even as our planes circle each other over Syria and Iraq. We owe it to the next generation to spare them the shadow of nuclear war that hung over us.

As the vastly stronger side in the confrontation, the west must act first. We should be looking for potential areas of cooperation with Russia which could begin to rebuild the shattered relationship. Terrorism and perhaps the governing of cyberspace are good places to start. Who knows where attempts at a thaw may lead? A Russia with a set of fruitful and constructive links with the west is far less likely to be tempted into Litvinenko- or Skripal-type outrages that would inevitably damage those links. Finally, once we have responded forcefully and legitimately to the Salisbury provocation, “the safety of the people” would be better guaranteed through cooperation than confrontation.

• Tony Brenton was British ambassador to Russia from 2004 to 2008