Rarely has a new government taken office facing such challenges or with so many hopes riding on its success. Nouri al-Maliki, the new Iraqi Prime Minister, promised on assuming office at the weekend that he would use “maximum force” to confront the terrorists. It is a promise that Iraqis, sickened by the daily bombings, desperately hope he can fulfil. So also do world leaders, none more so than President Bush and Tony Blair, who want to begin withdrawing troops as soon as possible but have insisted they will not do so until security improves.

Terrorists underlined the urgency of crushing the insurgency with a wave of suicide attacks, roadside bombs, mortar rounds and drive-by shootings at the weekend that killed at least 50 Iraqis. But Mr al-Maliki will find it hard to enforce government authority. His Cabinet, which met for the first time on Saturday, still lacks ministers of Defence and of the Interior — the key posts responsible for the country’s security. But after five months of wrangling since the election, the Prime Minister clearly hopes that, once a start has been made, it will be easier to fill these last two appointments.

Mistrust, however, is still running high. The Sunnis complain that the Constitution gives too much control over oil resources to the majority Shia and the Kurds, and fear that this will split the country. Parliament is to form a committee over the next four months to recommend amendments to the constitution. But even before Mr al-Maliki was sworn in on Saturday, about a dozen disaffected Sunni members walked out of parliament. Key Sunni leaders remained. But their colleagues should be condemned for a futile act of gesture politics.

World leaders are trying to do what they can to bolster his authority. President Bush called the formation of a unity government “a new day for the millions of Iraqis” and argued that this began a new chapter in US relations with Iraq. Mr Blair voiced similar sentiments. Both, however, have been careful not to link this development explicitly with a troop withdrawal. That would only encourage the insurgency. Instead, they want to phase the handing over of those provinces that can be pacified to full control by Iraqi security forces in a timetable that would be decided by the Iraqi Government.

How and when foreign troops should leave will be one of Mr al- Maliki’s toughest decisions. There may be a temptation to bolster secur-ity by delaying their departure. But the greater danger is a premature pullout, forced on Iraq by squabbling factions trying to win popularity by a tough stand against the coalition presence, or by domestic pressures on allied governments, especially in America, where support for the US commitment to Iraq is falling along with Mr Bush’s popularity.

Co-ordinating any phased departure with Baghdad will be a central theme of Mr Blair’s talks in Washington this week. There should be no rush for the exit.

Mr al-Maliki has announced a programme of 34 priorities to stabilise his country. Few can be achieved unless the insurgency is defeated. Some issues — promoting the independence of science faculties — would seem less vital than those lower down the list: controlling Iraq’s borders and ensuring that people no longer have to flee their homes. But at least these urgent needs have been recognised. Now Mr al-Maliki has to justify the hopes resting precariously on his shoulders.