For the past two weeks, the world’s attention has been focused on a potential strike by the United States and allies such as France, Germany, Canada and Turkey on the regime of Syrian President Bashar Al Assad as punishment for his purported use of chemical weapons in the suburbs of Damascus.

What is clear from the G20 meeting in St Petersburg is that there is strong opposition to the US acting unilaterally in striking Al Assad. The fact remains that all right-thinking people are sceptical of US intelligence that claims to have definitive proof that the regime used sarin. We remember all too clearly that Colin Powell offered the UN Security Council conclusive proof that Iraq possessed weapons of mass destruction. Eleven years on, in all of the rubble that is now Iraq, not one scintilla of evidence has been recovered.

Thankfully, the majority of British lawmakers remembered the lessons of Iraq in forcing David Cameron to change course from a military “solution”. President Barack Obama remains determined to go ahead with a punitive strike, but still needs the approval of Congress, which begins debating the move tomorrow.

Even if that approval is not forthcoming, the president can still authorise a military retaliation.

To do so would be a grave mistake.

Just as failing to allow the UN inspectors enough time to fully analyse their samples from Damascus would be a grave mistake.

Just as failing to have approval from the General Assembly of the UN would be a mistake. Just as failing to act on foot of a resolution from the UN Security Council would be a grave mistake.

If the US believes that it is the moral compass of world opinion, let it first act with the legitimacy of world opinion — with UN backing. If the US feels it is in a position to judge, let it sign on to international agreements that allow its soldiers and leaders be judged at the International Court of Justice — just as 190 other nations around the world have so done.