end this conflict, replace conflict with compromise, and allow the Yemeni people to heal through peace and reconstruction.”

Prior to the statement, the US has primarily avoided mentioning the conflict in Yemen despite the country selling the majority of the weapons used by Saudi Arabia to the Gulf country. Mr Pompeo's comments follow the Saudi government admitting they had premeditately murdered the dissident Saudi Journalist Jamal Khashoggi in Istanbul. Multiple countries, including Germany, have halted arms sales to Saudi Arabia following the murder of Mr Khashoggi. US Secretary of Defence James Mattis has also called for a ceasefire in Yemen within 30 days.

Mike Pompeo calls for an end to airstrikes in Yemen

James Mattis has also called for an end to airstrikes

He said: "The longer-term solution, and by longer-term, Ican easily be replicated today.

The next of Valentine’s twelve keys – each of which represents a different series of chemical reactions – describes making aqua regia, an acid mixture which can dissolve gold. This procedure was used by George de Hevesy in 1940 to hide two Nobel prizes from confiscation by the German forces invading Denmark – after the war the gold was recovered and successfully recast. The third of the keys describes making the dissolved gold ‘volatile’, allowing it to travel through the air as gold chloride and deposit red crystals elsewhere – a process of purification considered one of the greatest challenges of alchemy, not explained until independently rediscovered in 1895.

It is now believed that The Twelve Keys were published in this allegorical form in order