After more than 1,500 days of war in Yemen, in the midst of the world’s worst humanitarian disaster, reports of the Houthi withdrawal from Hodeidah port are a welcome but extremely fragile development, surrounded by suspicion and fear.

A Houthi pullout from Hodeidah, Saleef and Ras Issa ports would be one step in the implementation of the Stockholm agreement, but a very small step. There are much wider conflict dynamics to be addressed before we can talk confidently of moves towards peace.

At this point in the conflict, the chair of the all-party parliamentary group on Yemen, Keith Vaz MP, has chosen to write to the foreign secretary, Jeremy Hunt, to thank him for his efforts to secure peace in Yemen. The letter, co-sponsored by MPs Andrew Mitchell and Alison Thewliss, asks the government to “use every available tool to put pressure on our allies in the UAE and Saudi Arabia to bring about an end to the conflict”.

Curiously, at no point does the letter mention the uncomfortable fact of UK arms exports to the Saudi-led coalition, which have played a central role in creating the humanitarian disaster to which the government claims to be responding.

The UK government emphasises its largesse in budgeting £120m in humanitarian assistance to Yemen in 2018/19, and lauds its role in the peace process, including the Hodeidah developments.

These claims have become increasingly visible as domestic criticism has grown of UK arms sales to the Saudi-led coalition – including a legal challenge by Campaign Against Arms Trade – and other European states have adopted more restrictive policies. The UK is now out of step with most other EU member states bar France and its efforts to justify its position are becoming ever more absurd, to the point where Jeremy Hunt claimed at the end of March that it would be “morally bankrupt” not to sell weapons to the Saudis.

The key problem with the government’s position is that targeting the civilian population, which is illegal under international law, appears to be a core component of the Saudi-led coalition’s strategy in Yemen. Excessive civilian harm in the war is not an accidental side-effect of an otherwise effective military strategy.

So the effort to tally the balance sheet between arms on the one side and diplomacy combined with humanitarian aid on the other simply cannot work. No amount of funding can compensate for a military strategy that relies on harming the civilian population physically, economically and psychologically.

The government has been told this. UN experts note that Saudi-led coalition airstrikes have caused most civilian casualties in Yemen, and conclude that members of the Saudi-led coalition “have committed acts that may, subject to determination by an independent and competent court, amount to international crimes”.

The Yemen Safe Passage Group (a group that includes former ambassadors and former defence attaches) has told Jeremy Hunt that economic blockades and the military targeting of civilians are illegal under international law – and yet central to Saudi strategy. They too support calls for a suspension of UK arms sales until a sustainable peace has been achieved.

When former defence attaches and an anti-arms trade campaign group are making the same call, you’d think the government might stop and listen. Nonetheless, the government continues to mobilise ambiguity and doubt about what is happening in Yemen in order to argue that the risks associated with weapons sales are not “clear” – and hence that there is no reason to suspend them.

If the parliamentary group on Yemen wants to encourage Jeremy Hunt to use “every available tool” to bring the conflict to an end, that should include a suspension of arms sales to the Saudi-led coalition.

Indeed, in a report published almost exactly one year ago, the APPG itself concluded that “the UK should, based on current available evidence, immediately suspend arms sales to all parties that have been accused of breaching international law”.

A recent Dispatches programme suggested that Saudi bombing missions would have to stop within seven to 14 days if engineering support were halted. The UK government is in a position to force the warring parties to the negotiating table by withdrawing material, diplomatic and symbolic support for the coalition.

By omitting this from their call for action, signatories to the APPG letter are diluting the force of their good intentions and throwing away possibly the best chance to force a change in the dynamics of the war.

And in a context where the parliamentary committees responsible for scrutinising government arms export policy won’t even put arms sales to Saudi on the agenda for their latest inquiry, and where Tories are content to let the Labour chair of the committees take the heat for the committees’ failure, it is a bad sign for accountability in British politics as well as for Yemen that the APPG is in congratulatory mode.

• Anna Stavrianakis is a senior lecturer at the University of Sussex