This week marks the 13th anniversary of al Qaeda's September 11th attacks against America.

Many of the consequences of those attacks and subsequent U.S. interventions in Iraq and Afghanistan as part of the global war on terror have been tragic. Chaos in Iraq has infected Syria. An Islamic State (IS) that combines the most evil and vile elements of radical Islam has staked claims to great swaths of those states. Afghanistan totters on the brink of civil war. And massive amounts of American dollars have been wasted on these bitter and losing causes.

But suppose September 11th never happened. Suppose al-Qaida had focused on regional agendas instead of major attacks against the United States. Assuming he was not assassinated or died of natural causes, Saddam Hussein would still be exerting an iron grip on Iraq. A stable although horrific Sunni rule in Baghdad would remain a check on a Shia Iran. Syria might not have succumbed to a civil war in which at least 200,000 will perish and a large portion of its people displaced or made refugees. And IS would surely not be declaring a caliphate.

Would today be a safer place?

The answer, of course, is unknowable. Had the attacks not occurred, George W. Bush might not have won a second term. If John Kerry had been elected president, Barack Obama might still be in the Senate. That said, the best guess is that September 11th accelerated the effects of a dramatically changing international system. And today would not necessarily be safer absent September 11th.

The diffusion of power and globalization would still have eroded the state-centric Westphalian system in place since 1648. Individuals, groups and non-state actors would become empowered at the expense of states. Perhaps Edward Snowden and his revelations about U.S. electronic spying might not have resulted. But radical groups such as al-Qaida would still have been exerting powerful influence and greater reach.

The failure of governance and governments from Afghanistan to Zimbabwe would not have been lessened had September 11th not occurred. Political stability in Pakistan would be as illusive. Indeed, Taliban rule in Kabul could easily have stoked and aided Pakistani militants. Economic despair in Egypt would not have been relieved. And the so-called Arab Spring might still have erupted further destabilizing the Maghreb.

Vladimir Putin would still have had designs on Ukraine. The Arab-Palestinian-Israeli conflict manifested in Gaza would not have been eased. Ebola outbreaks in West Africa would not have been prevented. And the economic crises of 2007 and 2008 would not have been prevented.

China's so-called rise was unaffected by September 11th. Capitalism with a Chinese face meant that the question was never about economic growth but rather when China would emerge as a world economic superpower. And the rivalries and tensions in the various Chinese seas had persisted reflecting historic enmities dating back to well before World War I.

But September 11th did happen. And America's responses have not contributed to a safer world. Perhaps one of the most potentially damaging but largely invisible of these consequences is the pernicious threat to the constitution and to an open political system posed by radical Islam. Tempering the collision between protecting society from attack while preserving basic freedoms may be the defining issue of this decade for America.

Consider free speech, freedom of religion and due process. Is an American entitled to express the most extreme forms of radical Islam in public such as waging jihad and establishing a caliphate? Are women in full burqas above showing their faces when entering this country or if questioned by legal authorities? And is killing U.S. citizens who may be declared terrorists or enemy combatants without due process legal?

Countering Russia's encroachment into Ukraine and degrading and destroying IS are not missions impossible. Cogent strategies for both do not require superhuman effort. However, the more insidious and latent dangers to our society are not so easily resolvable.

For the time being, the assault on the constitution by radical Islam supercharged by a growing reach and perverted ideology that embraces suicide bombings and subhuman and barbaric practices to include beheadings and crucifixions has not been blunted or resisted. As we remember September 11th, we need to realize that much unfinished business remains.

If the United States and its friends and allies are to stop Islamic-based extremism, the challenges and threats that erode the constitution can no longer remain unfinished business.

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Harlan Ullman is Chairman of the Killowen Group that advises leaders of government and business and Senior Advisor at Washington D.C.'s Atlantic Council and Business Executives for National Security. His latest book, due out this fall is A Handful of Bullets: How the Murder of Archduke Franz Ferdinand Still Menaces The Peace.