The blast outside the UN headquarters in Baghdad, which killed top UN envoy Sergio Vieira de Mello and at least 16 others, was the deadliest attack in Iraq since coalition troops ousted Saddam Hussein. The suicide bomb that blew apart a bus in central Jerusalem six hours later, killing 20 passengers, was the bloodiest Palestinian attack since the June 4 agreement on a "road map" to peace brokered by US President George W. Bush.

Significantly, the two attacks come just as major milestones were being passed on both the road map to peace and Iraq's road to recovery. Israel was about to hand over two West Bank towns to the Palestinians. In Iraq, coalition troops were basking in the capture of Saddam Hussein's former vice-president, Taha Yassin Ramadan. The timing is no coincidence, of course. Driven by their insane millenarian fantasies in which Americans and Jews shall be wiped from the earth, the last thing the terrorists can abide is a measured progress towards peace and understanding.

Neither was the targeting of the UN by the terrorists in Baghdad coincidental. Only last week, the UN Security Council gave its approval to the recently formed Iraqi Governing Council, which has been charged with writing a new constitution. It is possible, too, that the targeting of Mr de Mello was connected with his role as UN head of operations in East Timor, the liberation of which from Indonesian occupation is one more source of the resentment that the Islamist fanatics harbour against the West.

It also illustrates that, contrary to the argument of some of those who opposed the war in Iraq, the recovery process would likely be just as difficult and obstacle-strewn if the UN, rather than the US, were in charge. Those who think that the terrorists have some sort of respect for the authority of the UN are hard-pressed to explain why, for example, al-Qa'ida was caught plotting to blow up the UN General Assembly building in the mid-1990s. In the videotape broadcast on Al-Jazeera satellite television on November 3, 2001, Osama bin Laden railed against the UN as "nothing but a tool of crime" and the source of Muslim suffering and humiliation.

While the perpetrators of the Baghdad bombing are unknown, there is no doubt that the presence of US troops in Iraq, combined with its porous borders, make the country a magnet for terrorist groups, including al-Qa'ida. It is also well within the al-Qa'ida modus operandi to shift the focus of attacks away from military targets, and onto civilian targets and infrastructure: make ordinary Iraqi's suffer enough, and they will lose confidence in those who are trying to help them.

There is no point in muddying the responsibility for such outrages, as both the Democrats and Greens did yesterday as part of their increasingly unseemly struggle over the fringe vote. For Greens leader Bob Brown and Australian Democrats leader Andrew Bartlett to say that the bombing would not have happened if Australia, Britain, and the US had not joined forces to topple Saddam Hussein is disgraceful, because it is code for the suggestion that we, and not the terrorists, are to blame for Mr de Mello's death, and the other victims. Would senators Brown and Bartlett prefer an Iraq that was still operating as Saddam Hussein's personal charnel-house? Rather than blaming the US, our best efforts must be directed towards ensuring that, with an election year looming, there is no temptation for President Bush to cut and run before the job in Iraq is complete. And the best way we do that is by offering our full support, and maintaining our modest military involvement.

The bomb in Jerusalem was just as devastating, driving what may be the final nail into the coffin of the seven-week-old ceasefire. Several extremist groups have stepped forward to claim responsibility. Their argument that the bombing is a justified retaliation for Israel's ongoing attacks on their own commanders is totally without force. Attacks on Israelis have slowed, not stopped, since the ceasefire. If the Israeli Government has a bead on terrorist ringleaders plotting mayhem, how can it be expected to do nothing? There is no equivalence between that and randomly blowing up a bus whose passengers include women, children and babies.

Humoured by his fans worldwide, including among the membership of the EU, Yasser Arafat clearly has no intention of going quietly, and letting Palestinian Prime Minister Mahmoud Abbas pursue the road map to peace. If Arafat told the militants to disarm, they would. But as long as there is an armed militia for every Palestinian faction, rather than a single force under the authority of the Palestinian Authority government, the road map will be one step forward – and then a bomb, blowing everything back into ruins.