On Tuesday, Jean-Claude Juncker wrote to Vladimir Putin to congratulate him on his electoral success, presumably taking inspiration from the list of global demagogues and dictators who were also quick to send their congratulations, from President Nicolás Maduro of Venezuela to President Alexander Lukashenko of Belarus.

President Trump followed, but at least his advisers had given express instruction: “DO NOT CONGRATULATE”. Which, of course, the American president ignored. Shamefully, neither Juncker nor Trump mentioned the deployment of Russian-made chemical weapons in Salisbury, nor did they raise concerns about the legitimacy of the so-called “election” we have just witnessed in Russia.

Michael Link, the German MP who led the independent OSCE election-monitoring mission to Russia, has been clear that they found there was no “real choice” for voters. Voters were herded to polling booths, and ballot boxes stuffed, while the main opposition leader Alexei Navalny was banned from standing. So, no, this is no time for congratulations. Yes, we will always need dialogue with Russia, but closer ties must be conditional on respect for the rule of law.

Too often, the west has rolled over while the Russian bear mauls our liberal democracies, corrupts our political systems, hacks our political parties, pollutes our online ecosystems, and seeks to drag European countries back to a violent and divided past. While European leaders have responded with warm words of support for Britain in the wake of the Salisbury incident, we need to deliver a serious collective European response that can be framed as part of a new EU strategy towards Russia.

With this new strategy we should show to Mr Putin that his violations of international law have clear consequences, but also open up the perspective of cooperation and engagement, provided Russia starts delivering on its commitments under international law and starting with the implementation of the Minsk agreements. Instead of sending congratulation letters, EU leaders, and in particular high-representative/vice-president Federica Mogherini, should therefore come up with such a proactive strategy. First of all she should push for clear EU-wide sanctions in response to the Sergei Skripal case. If there is one thing that truly alarms the mafia elite surrounding Putin, it is the prospect of being denied access to their European villas.

The EU and Nato need to reopen channels of communication to reduce the risk of misunderstandings and miscalculations

It is essential that Brexit does not weaken foreign policy and security cooperation across Europe. The European parliament’s proposal for an umbrella EU–UK Association Agreement sets out a framework for delivering this. We must ensure security and defence agreements are in place before the end of the transition period. We need a comprehensive, Mueller-style, EU-wide investigation into the extent of Russian influence on our democracies, economies and political systems, which can set out credible responses. It is wrong that Russian billionaires can buy EU citizenship in Malta, launder money in London property through shell companies and seemingly donate to European political parties at will.

At the same time we have to overcome the current stalemate where EU-Russia contacts are frozen, but member states continue developing bilateral channels with Russia, often serving narrow national interests. The EU and Nato need to reopen channels of communication to reduce the risk of misunderstandings and miscalculations – as was the case during the cold war.

A new strategy could be built on the logic of the Helsinki process of the 1970s. A Helsinki 2.0 would strengthen European security architecture through opening up the perspective for a political and economic engagement with Russia. In exchange for full respect of the Minsk agreements, compliance with international law and also progress when it comes to free and fair elections and respect for human rights inside Russia, the EU would not only lift economic sanctions but progressively deepen political and economic cooperation.

This strategy would also make clear that our dispute is with the current Russian government, not with the Russian people. We should therefore open our universities and labour markets to the best and brightest young Russians citizens and unilaterally facilitate visas for Russian citizens. Support for independent civil society activists, the free media and NGOs in Russia should be enhanced.

Most importantly, we have to swiftly build a Defence Union, as a European pillar of Nato. For decades, we have relied on the US and failed to invest in modern defences and the integration of our capacities. Many European politicians refuse to make the case to the people for a European defence and security capacity, for fear of falling foul of the Eurosceptics that Putin sponsors; we find ourselves trapped in a vicious cycle.

I hope the younger generation of current European leaders, from Emmanuel Macron to Leo Varadkar, will have the courage to be bolder and make the case for an integrated European defence.

Many don’t want to accept the truth because it means hard choices have to be made, but the reality is that the Kremlin is again at war with our liberal democracies. If we don’t respond with a new long-term strategy, Putin will be emboldened.

• Guy Verhofstadt is chief Brexit representative for the European parliament