The horror in eastern Ghouta at the weekend was truly sickening. People foaming at the mouth, children suffocating, scores dead. We’ve seen these kind of images before, but they do not become less shocking. From the evidence we’ve seen so far it appears that the latest chemical attack was likely by Mi-8 helicopters, probably from the forces of Syria’s murderous President Assad.

In London the cabinet meets today – deciding on Britain’s response to this appalling act.

The UK’s response must have the backing of parliament. That’s why it is absolutely essential that any military action is debated and voted on by MPs, not simply decided at cabinet level. Interestingly, five years ago Boris Johnson was asked about whether there should be a vote on military action in Syria. His answer was emphatic: “there’s got to be a vote”.

A whipped vote, where MPs are told which way to go by their leaders, isn’t good enough either. Issues like this – where MPs are entrusted with deciding on whether to send RAF pilots into dangerous skies to drop 1,300 kilogram, £790,000 missiles on foreign lands – should be decided according to the evidence and our conscience – and the party whips should stay out of it.

While I will always listen to all the evidence before making a decision, I remain to be convinced that a military attack would deter, rather than escalate, conflict and suffering in the region. I’m sceptical about the impact that “gesture bombing” in Syria can have without a much wider strategy, I am deeply worried about the risks of escalation – Russia has already threatened to attack the “source” of any missiles aimed at Syria – and I remain opposed to any attempted “regime change” imposed by the West.

Look at modern-day Libya, at the rise of Isis in Iraq, at the resurgent Taliban – the long-term impacts of our recent military interventions are a bloody stain on our country’s record. Syria is a tinderbox, the theatre for proxy wars by numerous different actors, and is already deepening the tensions between Israel and Iran. For Trump to threaten war by tweet is an insult to all those whose lives will be on the line when it comes to engaging in such actions.

To drop bombs on Assad without a serious, thought-out strategy, and a plan about what happens next, risks making a horrific situation even worse. It is this issue that will be the key test of any proposal made by the British government – they must prove that they are thinking about the long term and not blindly following Trump into further military folly that risks bringing Russia’s military face to face with our own. It is on these grounds that, on the evidence I’ve seen so far, I believe that the risks of such an action outweigh the benefits.

History warns us against reckless military action, but it should also teach us that tough action doesn’t have to mean bombs and bullets. That’s why I believe that Britain should be urgently exploring every alternative avenue to further bombing. For a start that must mean cracking down on Russia, Syria’s bloody-handed ally. We need to hit Putin where it hurts. That means both unilateral sanctions, including a crackdown on Russian money and property in London – and international ones too.

It’s worth noting that US sanctions against Russia are finally beginning to have an effect. New US sanctions on seven oligarchs, 17 top officials and 12 companies led to tens of billions of dollars in losses on Russian markets within just a few hours on Monday, and the rouble recently suffered its biggest daily fall in over three years. We now need to double down on these actions.

We should also be straining every sinew to get all relevant parties around the table for discussions on how to broker peace between the region’s key players: Iran, Russia, Saudi Arabia, Turkey, Kurdish leaders and Israel. To be a diplomatic leader, and set an example for the world, we must urgently get our own house in order too. That’s why we must immediately end the hypocrisy of selling arms to Saudi Arabia, and be clear about our opposition to Israel’s recent violence against the Palestinians.

In the longer term, and in recognition of the appalling failures of recent years (Afghanistan, Iraq, Libya and elsewhere) we must expend serious and sustained effort to enhance and expand UN peacekeeping and peace-building capabilities. The mechanisms for action at the UN need reform too – particularly the workings of the security council. Britain must also urgently take more refugees from the region too, to join those who have already settled and started making a life here.

Whatever happens I would urge politicians of all sides to avoid using the destruction in Syria, and any discussion of our response, as a stick to beat political opponents here in the UK. Those who refuse to join a march to war are not “traitors” just as many of those in favour of military action do so because they believe it will minimise bloodshed. Ultimately in this debate no option is without its risks or consequences.

It now rests on the government to make its case to an unwhipped House of Commons, so MPs can decide for themselves while free from the dictats of a party machine.