The mass shooting last month at a nightclub in Orlando and the unbroken barrage of attacks in Turkey, Bangladesh, Saudi Arabia, Iraq and elsewhere have dominated news reports, reminding us that the threat of terrorism is real and constant.
Not surprisingly, Americans are intensely focused on the question of how to protect the homeland. Polls show that it is among their top priorities, and they are not confident that the government is doing everything it can to keep us safe in what has been called a "forever war."
But what we learned from the 9/11 attacks remains true today: There is no silver bullet that will protect us. It will take a multi-layered approach that involves national security agencies, state and local law enforcement and ordinary citizens. And we cannot expect total success soon. CIA Director John Brennan says we have a ways to go before we can claim significant progress.
First, the threat of terrorism is serious and urgent. But it is not, as some fear, an existential threat. The basic nature of our institutions and values is sound, even if they are under stress.
The threat is complex and challenging, however, and it is made more so because it may include direct attacks by ISIS and other groups as well as "lone wolf" actions by individuals who were inspired by such organizations or radicalized by what they saw on the internet.
Some of the most horrific incidents in the U.S., including the shootings that killed 49 people in Orlando, the Boston Marathon bombing and the attack on a local government center in San Bernardino, Calif., appear to fall in the second category.
What can we do? The list is long and familiar.
First, we need to continue military action against groups that threaten and organize attacks. We have to take the fight to them; we cannot wait until they attack us. We must go after so-called safe havens with airstrikes, drone attacks, special operations and other tactics. If we do not, they will attack us again.
Recent strikes by the U.S. and its allies have reportedly killed hundreds of ISIS fighters and several key leaders of terrorist networks, including an ISIS deputy minister of war. We have taken back land that ISIS previously controlled in Iraq and Syria, including the important city of Fallujah. This success keeps terrorist leaders off balance; it makes them focus on protecting themselves and adapt their tactics.
To defend ourselves at home, we rely on law enforcement, including the FBI and state and local police. To them fall the heavy responsibilities of detection, investigation, surveillance and prevention. The federal government is appropriately providing local agencies with assistance in training, communications and intelligence gathering.
Everyone's preferred counterterrorism tool is sharper intelligence. If we can identify terrorists early on, we can prevent the attacks. We have made real strides since 9/11 in improving the gathering and sharing of intelligence, but we can and must do better.
ISIS and its allies have become quite sophisticated in their use of social media, so we must match and exceed their skills and blunt the appeal of their message.
Border control is another piece of the puzzle. An early line of defense is to prevent the smuggling of weapons and drugs and keep bad guys from getting into our country. Keeping track of suspicious individuals entering and leaving the U.S. is a huge but essential task given the tens of thousands of people who cross our borders every day.
In a related matter, our approach to immigration must prioritize our national security interests, and sharpen enforcement of immigration laws. With up to 12 million immigrants in the U.S. illegally, we cannot deport them all at an acceptable fiscal and social cost, so we should focus on removing those who are convicted of serious crimes or who threaten public safety.
We also need to better understand who, among the many disaffected people in our country, is likely to turn to violence. Most will not. But we are not very good at understanding what causes some individuals to move from expressing radical opinions to carrying out attacks on their neighbors.
But government can't do it all. Businesses, universities, sports organizations and other institutions have stepped up their emergency preparedness, sharing information and raising awareness of the importance of being alert to signs of danger.
Finally, citizens are the first line of defense in protecting the homeland. "See something, say something" has become a cliché, which our citizens simply must take to heart.
This includes, importantly, Muslim American citizens and immigrants. Strong and ongoing cooperation and communication with Islamic communities may be the most important tool we have to identify radicalized individuals and prevent attacks. The vast majority of Muslims abhor ISIS and other groups that organize and sponsor violence. Islamic organizations and communities are in position to take the lead in the U.S. in discrediting terrorists.
And we need to do all this while protecting fundamental American values of individual privacy and the openness and transparency of government institutions. This is a balancing act, but we have to protect the civil liberties of Americans at the same time we aggressively oppose terrorism.
Both supporters and critics of our homeland security polices agree that we simply have to do all of this better, faster and more effectively.
The idea that we are engaged in a war against terrorism can be misleading, because it suggests the war will end decisively. That won't happen. Experts agree that these attacks will continue and that we must use all the tools we have to prevent them.
Fundamentally, this forever war is a war of ideas. Bad ideas, like communism and fascism, can be defeated, but not easily or quickly and only with significant resources. There will be victories and defeats, but we must have confidence that we will prevail.
Lee H. Hamilton is a Distinguished Scholar, Indiana University School of Global and International Studies; Professor of Practice, IU School of Public and Environmental Affairs; and Senior Advisor, IU Center on Representative Government. He served as U.S. Representative from Indiana's 9th Congressional District from 1965-1999.