In his first House of Commons appearance as Foreign Secretary, Boris Johnson was rightly damning of the Russian bombardment of Aleppo. He also exposed the hypocrisy at the heart of UK foreign policy in the Middle East.

Calling for protests outside the Russian Embassy in London, Johnson said he wanted attacks on hospitals to be “properly and fully investigated with a view to assembling the necessary evidence and ensuring that justice is done.” He added that he was “very attracted to the idea of holding these people to account before the International Criminal Court.”

He’s absolutely right. The bombing has had a terrible human cost, with hundreds of civilians killed since the ceasefire broke down last month. If international humanitarian law is to mean anything, then those responsible for war crimes must feel its full weight.

Where Johnson has been nowhere near as strong or principled is in his response to the humanitarian catastrophe that Saudi-led coalition forces have inflicted on Yemen. Last Saturday saw devastating air strikes on a funeral in Sanaa, Yemen, which killed at least 155 people and wounded 500 more. Johnson’s first public response was to issue a tweet. He made no calls for an end to attacks on civilian areas or for those responsible to be dragged before the ICC.

Scores dead in blasts at funeral in Yemeni capital

The lives of people in Yemen are just as valuable as those in Syria. So why was his response so much weaker?

One key difference is that the UK has been complicit in the Saudi-led attacks. From the outset, the then Defence Secretary, Philip Hammond, pledged to “support the Saudis in every practical way short of engaging in combat.” The Government has stayed true to its promise, having provided training and political support for Saudi combatants, and having licensed over £3.3bn worth of arms since the bombing began last March.

Right from the start, Saudi-led forces have been accused of hitting civilian targets. Schools and hospitals have been destroyed and more than 10,000 people have been killed, with a number of the attacks being linked to UK arms. Despite detailed reports of humanitarian law violations from the United Nations, Amnesty International and other respected organisations, the UK has stuck rigidly to the line that the best people to investigate Saudi Arabia for war crimes are the Saudi Arabian Government.

“It is important that the Saudi Arabian-led Coalition in the first instance conducts thorough and conclusive investigations into incidents where it is alleged that international humanitarian law has been violated,” Johnson said in a written statement last month. “They have the best insight into their own military procedures and will be able to conduct the most thorough and conclusive investigations.”

The limited steps the Saudi regime has taken prove how bad a policy this is. During the summer the Saudi-led coalition published its own report into the conduct of its forces. Needless to say it was a whitewash, only analysing eight of the hundreds of violations it has been accused of and largely exonerating itself of any wrongoding.

Regardless, the UK Government stuck to the same line in light of Saturday’s bombing. On Monday, a spokesperson for Number 10 said: “Until we have a full assessment of the facts on the ground, it would be inappropriate to comment further... We want the Saudis to carry out their investigation.”

This is appalling logic. Like the Assad regime in Syria, the Saudi administration cannot be trusted to run free and fair elections and has shown a contempt for human rights. How can it possibly be expected to investigate itself for war crimes?

In pictures: Protests around the world over Saudi executions Show all 7 1 /7 In pictures: Protests around the world over Saudi executions In pictures: Protests around the world over Saudi executions Protests around the world over Saudi executions Iranian and Turkish demonstrators hold pictures of Shiite cleric Sheikh Nimr al-Nimr as they protest outside the Saudi Embassy in Ankara, Turkey, In pictures: Protests around the world over Saudi executions Protests around the world over Saudi executions Kashmiri Shiite Muslims, carrying a placard with the portrait of Sheikh Nimr al-Nimr, shout slogans during a protest in Srinagar, Indian controlled Kashmir, In pictures: Protests around the world over Saudi executions Protests around the world at Saudi executions Indian police used tear smoke and rubber bullets to disperse Shiite Muslims who were protesting after Saudi Arabia announced the execution of Shiite cleric Sheikh Nimr al-Nimr on Saturday along with 46 others, including three other Shiite dissidents and a number of al-Qaida militants. In pictures: Protests around the world over Saudi executions Protests around the world over Saudi executions Shane Enright, Global Trade Union Advisor for Amnesty International, addresses demonstrators as they protest outside the Saudi Embassy in London, following Saudi Arabia's execution of 47 prisoners in one day, including a top Shiite cleric In pictures: Protests around the world over Saudi executions Protests around the world over Saudi executions Iranian protestor burn pictures of a member of the Saudi royal family in front of the Saudi Arabia embassy in Tehran, Iran, 02 January 2016. Protesters have stormed the Saudi embassy building in the Iranian capital of Tehran early Sunday amid backlash over the execution of a prominent Shiite cleric. Flammable substance was seen thrown at the building as protests gained steam over the execution of Sheikh Nimr al-Nimr. Reports states, protesters taking down a Saudi flag and burned the building. In pictures: Protests around the world over Saudi executions Protests around the world over Saudi executions Shiite Muslims hold placards with pictures of Saudi Shiite cleric Sheikh Nimr al-Nimr, whose execution in Saudi Arabia was announced Saturday, during a demonstration to condemn his execution, Sunday, Jan. 3, 2016 in Peshawar, Pakistan In pictures: Protests around the world over Saudi executions Protests around the world over Saudi executions A Kashmir Shiite Muslim shouts slogan from Indian police vehicle after he was detained during a protest in Srinagar, the summer capital of Indian Kashmir,

Johnson is right to call for an end to the bombing of civilian areas and for investigations into war crimes against the people of Syria. At the same time, there are also major steps that he can take right now to alleviating the suffering of people in Yemen.

If Johnson and his colleagues are serious about peace and about the UK holding a positive influence on the world stage then they must stop the arms sales, end their support for the Saudi bombardment of Yemen, and hold the UK’s so-called ally to the same standard as other aggressors.