As Labour leader, Jeremy Corbyn has been clear that he understands our responsibilities to one another does not stop at the borders of Britain. In every speech I have seen him give, he has spoken of international solidarity: of Colombian trade unionists, of the Spanish Civil War, of protesters in Saudi Arabia.

It is that sense of solidarity we must show to the people of France after this weekend’s atrocity. A sense of solidarity I would hope is shared by all in the UK, and that this country’s labour movement will lead.

It is not just that these attacks happened on our doorstep, although they did – it is quicker (not to mention cheaper) for me, for instance, to get from my flat in South London to Paris than it is to get to my childhood home in East Lancashire.

It is that this attack, as Corbyn correctly said yesterday, “is an attack on all of us”. This is not hyperbole. The likes of ISIS do not see borders. They do not even see oceans. They see a common enemy, and when they attacked Paris on Friday night, they attacked London too. And Manchester. And Edinburgh and Glasgow. And New York, Washington, Madrid, Berlin and Rome. They see one common enemy.

I would hope they are right. Trite as it sounds, what they hate most about us is our commitment to democracy and freedom, perhaps most of all the freedoms to love and worship who we please. When Corbyn said yesterday spoke of our pride “to live in a multicultural and multi-faith society”, he was, again, absolutely correct. It is that that sets up apart.

Corbyn wrote to President Hollande, committing the Labour Party to support “every effort to bring to justice the perpetrators of these despicable acts.” It is our duty to ensure they are not empty words.

He wisely cancelled a speech yesterday where he had intended to argue for a foreign policy that meant the UK had “more independent relationship with the rest of the world”. That speech should now never be given. It goes against his best internationalist instincts. What we need now is to stand closer in solidarity with our allies, and build stronger relationships, not try and isolate ourselves under a guise of independence.

In a statement, Corbyn also warned against a response that would “feed a cycle of violence”. No one wants that. ISIS are part of no cycle, though. They are the violence. It is central to their hateful ideology. They murdered 41 people in Lebanon on Thursday. They have murdered countless more in Syria and Iraq. They enslave people, drive them to die on mountainsides, and behead them. It is not just the West they hate, but humanity.

Hollande has said that what was committed was an “act of war”. His appears keen to invoke Article 5 of NATO’s treaty, which states that an attack on one ally is an attack on all. Given Corbyn’s own words, he cannot now shy away from what comes next. It is impossible to argue that Thursday’s approach to ISIS is also Monday’s.

Reports suggest that one bomber had tried to enter the Stade de France with a ticket for France v Germany. I had turned down tickets for this week’s match between England and France at Wembley, but following events changed my mind and bought tickets yesterday. I will go to the football with my friends this Tuesday to pretend that nothing has changed; and we will sing La Marseillaise because things have. It is the reality Labour must face.

Symbols are great: I sing the French national anthem, our landmarks are lit up with the tricolore, we change our social media profile pictures. There is nothing wrong with any of it. But solidarity, genuine solidarity, means more than it. Those symbols won’t mean much to the Kurds or Yazidis still suffering daily, the next aidworker kidnapped, or the innocents slaughtered in the next major ISIS terrorist attack.

Jeremy Corbyn knows that solidarity means more. It is why he has spent decades going down to picket lines to stand shoulder to shoulder with strikers. It is why he hails those who went to fight the fascists in Spain. It is why a letter expressing solidarity is never enough when you can do more. We must keep our word.