Leading article: The Arab League must withdraw

If there was ever much hope that Bashar al-Assad might be willing to compromise, it has now been comprehensively dispelled. Far from moderating his position, the Syrian President's defiant speech this week makes clear that he is digging in. Alongside wearily familiar lines blaming foreign conspiracies for the rebellion that has claimed more than 5,000 civilian lives since March, he made alarming promises to crack down with an "iron fist" on the terrorists causing such upheavals.

So much for the Arab League mission to oversee the peace plan the Syrian President mendaciously signed up to in December. Indeed, such is the swagger in Damascus that President Assad now openly scorns the threat of expulsion with which the League pressured him to sign. It is not hard to see why. Not only has the delegation not stopped the violence, its observers have been corralled, manipulated, and used to buy time for the obnoxious Syrian regime. Enough is enough. It is time to call a halt to a charade that works in no one's favour but President Assad's.

The credibility of the Arab League mission has been suspect from the outset. With only 165 observers at its full complement, the delegation was never anywhere near large enough to cover a country the size of Syria effectively. Its reliance on the regime for logistical and security support rightly sparked concerns about its independence. And the leadership of General Mustafa al-Dabi – a supporter of the Sudanese President, wanted in the Hague over genocide in Darfur – also raised eyebrows. After weeks of escalating violence, the mission is now unravelling. That one of its observers has quit, branding the entire operation a "farce", accusing the regime of gross crimes, and describing the situation on the ground as a "humanitarian disaster" only confirms sceptics' worst fears.

Hillary Clinton, the US Secretary of State, has hinted that the Arab League mission should not continue indefinitely. She is half-right. It should not continue at all. Simply by their presence, the monitors are lending legitimacy to a wholly illegitimate regime. They should be withdrawn forthwith.