The good news is that US President George W. Bush is not going to invade Iran before he leaves office. The bad news is he is attacking Pakistan instead.

For years the White House has issued urgent warnings about the threat from Iran at every opportunity, accompanied by the threat that "all options are on the table" if Iran didn't stop its alleged nuclear weapons programme.

Since we knew how Bush acted in the case of Iraq's alleged nuclear weapons programme, there was good reason to worry that he might actually carry out his threat.

Late last year the US intelligence services deliberately undercut his case for war against Iran by releasing a joint assessment that concluded Tehran had stopped its nuclear weapons programme in 2004. That killed Bush's hopes of getting the American public to back an attack on Iran.

So the White House has gone entirely silent on Iran. But about two months ago, according to information leaked just last week, Bush authorised US military attacks against suspected supporters of the Taleban and al Qaeda on Pakistani soil - without the permission of the Pakistani Government.

Pakistan is a US ally, even though the great majority of Pakistanis wish it wasn't. There are few unbreakable rules in international affairs, but not attacking your ally is definitely one of them. Except if you are American, in which case it's okay, or so the White House appears to believe.

The latest incident, just after midnight on a Monday morning, began when seven US helicopter gunships and two troop-carrying Chinook helicopters landed near the Pakistani border in the Afghan province of Pakhtia.

US troops got out and tried to cross the border into Pakistan, presumably in search of some "terrorist" target.

According to local officials, Pakistani paramilitary troops manning a checkpoint fired into the air to warn off the Americans while local tribesmen took up defensive positions.

On this occasion, the US soldiers stopped. With nobody around to stop them, however, another American ground force attacked a target in Pakistan's South Waziristan province on September 4 and, according to local witnesses, killed about 20 people, including women and children.

The local witnesses may be exaggerating, but the fact American troops carried out an act of war on Pakistan's territory without informing Islamabad, is not disputed. And there have been other recent American attacks, involving missiles fired at suspected terrorist targets, in which innocent Pakistani civilians have unquestionably been killed.