The morning after Sept. 11, 2001, you didn’t have to be in New York or Washington to feel that the world had changed.

America was under attack, thousands of Americans had been killed. Even the Maine woods and the shores of Casco Bay were different places because America was a different place.

Now, nearly a decade later, another event has rocked our consciousness, changing the way we see the world. The murderous mastermind of 9/11 is dead, and the most frustrating symbol of a great nation’s vulnerability to attack by a hit-and-run terrorist network with no homeland to defend has been erased.

There is still a lot we don’t know about the meaning of this event, but what we do know about a world without Osama bin Laden is this: The war on terror is not over and the ongoing fight will continue to be expensive, both in loss of life and national resources. While bin Laden was a powerfully emblematic figure, and his survival provided a reason to doubt America’s power, he was by many accounts no longer the operational leader of a global organization.

His al-Qaida network has evolved into a loosely organized collection of regional terrorist cells united primarily by their common determination to wage war on the United States in particular and Western culture in general. Bin Laden may have provided these cells with political and spiritual inspiration as well as financing and other resources, but his death will not make them dry up and disappear.

What lies ahead

If anything, his death at the hands of U.S. military operatives will inflame his disciples’ hatred of the West and ignite a desire for revenge.

But while the demise of bin Laden did not end the war on terror, the way that he was hunted down and killed may tell us how that war is likely to be fought in the months and years ahead.

President Obama was criticized by some during his 2008 campaign for saying that if he had reliable intelligence on bin Laden’s whereabouts, he would take unilateral action, even if the terror leader were in another country.

That is exactly what the president did on Sunday, and his high-risk decision to send a commando team into a populated neighborhood in a major Pakistani city could only have been made by him alone. A president who is often accused of being too slow to act or too political in his decision-making was neither, and the world is better for it.

It may seem inappropriate to discuss politics in the wake of such a monumental moment in American history, but the political courage required for the president to take the action he did cannot be discounted. If the commandos had not been dispatched, the world would have been none the wiser.

But if something had gone wrong, like President Jimmy Carter’s failed attempt in 1980 to rescue hostages in Iran, Obama would have been held responsible; his political obituary might have been written on the spot.

What the United States demonstrated on Sunday is that when terror cells move and attack without regard for international borders, we must and will pursue them the same way. And if that means violating the sovereignty of even a nominal ally like Pakistan, we will do it.

We also learned that the long-stated U.S. policy that we do not assassinate individuals has some loopholes. Reuters reported Monday that the operation was not designed to capture bin Laden – it was a “kill mission” that clearly achieved its goal.

Other bad actors

Whether that has implications for other enemy leaders who dig in around the globe remains to be seen, but it seems reasonable to wonder if a tyrant such as Libyan dictator Moammar Gadhafi feels less secure today than he did last week.

The hunt for bin Laden was years in the making. There were missteps along the way, but we clearly learned from them.

And there were sacrifices, starting with the nearly 3,000 families referred to by the president when he announced that “justice has been done” for the victims of 9/11— families who have lived the last decade without a husband, wife, son, daughter, brother or sister. There were, and are, thousands of U.S. military men and women who put their lives at risk far from home, and their families who sacrifice so much while their loved ones serve our country.

We have lived in a changed world since bin Laden’s gang brought the battle to our soil in 2001. Now, it’s our country that has projected dramatic and effective force to the other side of the world, flawlessly carrying out a mission on an illusive target.

The long-term significance of bin Laden’s death may not be known for years to come.

But we know that the world has changed. And we know that justice has been done.