And while the four terrorist incidents happened in the United States it was a tragedy of global consequence not least because more than 90 countries lost citizens in the attacks.

It also led to the war in Afghanistan, a conflict that remains unresolved to this day, with Australian forces still in the country as they have been since October 2001.

Australian governments have always justified involvement in Afghanistan by stressing that our own national security is greatly enhanced by denying al-Qaeda and other jihadist groups a haven, and that this is best done by helping to build a more secure and democratic Afghanistan.

Sadly that future seems as far away as ever, with the Afghan government - although elected - maintaining only a tenuous grip on the capital Kabul and outlying area while the Taliban forces, displaced in 2001, remain de facto rulers of much of the country.

Indeed America is now negotiating directly with the Taliban in an effort to extricate itself from the conflict.

The influential American magazine called Foreign Policy says after 18 years of war, thousands of lives lost, and hundreds of billions of dollars squandered, the United States has accomplished precisely nothing.

It says the Kabul government is irredeemably corrupt, the Taliban had sanctuary and support in Pakistan and the claim that it was necessary to deny al Qaeda a "safe haven" was increasingly dubious, especially once Osama bin Laden was dead and that terrorist group had spread to many other countries.

"Trying to turn Afghanistan into a modern, Western-style democracy was an act of extraordinary hubris, and all the more so when U.S. leaders told themselves they could do it quickly," Foreign Policy said.

If the US does withdraw so most likely will the 300 ADF personnel deployed there.

It is terribly sad news especially for Afghan women who face a return to second class citizens under a renewed Taliban government.