Donald Trump's apparent shift in how to tackle Bashar al-Assad has added further knots to the new president's already tangled Syria policy.

At first sight, his willingness to promise action over the heinous attack and defend the human rights of innocent Syrians was a welcome departure from his narrow, America First, doctrine.

For the first time, he appeared to be stepping up to his position as the "Leader of the Free World".

Mr Trump acknowledged on Wednesday that he could not stand by and do nothing in light of the devastation of Tuesday's chemical weapons attack that left up to 100 people dead including more than 30 children.

While he refused to give any details on how American policy could change and said he would rather have nothing to do with the Middle East whatsoever, the president, facing the most significant foreign policy challenge of his three-month-old presidency, acknowleged: "It is now my responsibility."