Nearly 15 years after the 9/11 attacks, we are still debating what to do to fight terrorism.

Following the attacks in Brussels, President Obama called for bringing the killers to justice, Donald Trump called for waterboarding captured terrorists, and Hillary Clinton called for increased surveillance and interception of communications.

Ted Cruz wants proactive policing in Muslim communities to uncover radicalism, Bernie Sanders wants the international community to come together, and John Kasich wants heads of state to assemble teams to examine vulnerabilities and close security gaps.

Cruz would try “carpet bombing” ISIS territory and Trump would use overwhelming military power against the Islamic State.

Trump also would control the borders more tightly, an idea derided by Clinton, who said America doesn’t “hide behind walls.”

We’ll see.

There are problems with every approach. Overwhelming military force leaves unanswered the question, “And then what?” Will we permanently station U.S. troops to hold the territory and protect the innocent population from the seething rage of rival factions? It’s an option some have supported in the past. Others have waited in line for six hours to rally for candidates who are against it.

The plan to bring terrorists to justice suffers from two major problems. Arresting a terrorist seems only to create a job opening in the organization. And U.S. courts are not friendly to secret intelligence sources or coerced confessions. It’s easy to sneer at “reading terrorists their Miranda rights,” but our justice system protects the rights of the accused, and if we weaken those protections, we all will be at greater risk of wrongful convictions.

Military tribunals are an option for captured foreign terrorists, but Obama wants to close the prison at Guantanamo, which may complicate the process.

Increased surveillance of communications and “pro-active policing” risk further violating the rights of innocent Americans. The Fourth Amendment guarantees the right to be secure from unreasonable searches and seizures and requires the government to get a search warrant. The Fourth Amendment survived the Civil War, the First World War, the Second World War, the Korean War, the Vietnam War and the Cold War. Are we going to lose it in a war against terrorists?

It’s a great idea to have international cooperation and to close security gaps. We’ve been trying to do that for a lot longer than 15 years.

That leaves border control. There is room for improvement on that.

Rep. Ron DeSantis, R-Fla., chairman of the House Subcommittee on National Security, recently held a hearing on the use of asylum claims to avoid deportation. It has long been U.S. policy to allow immigrants, particularly women and children from Central America, to stay in the United States if they assert that they have a credible fear of persecution at home.

In the past, many asylum seekers who entered the U.S. illegally were held in custody until their cases were heard in court, but in 2009 Obama changed that policy. Now anyone who says the magic words “credible fear of persecution” is released and given permission to work in the U.S.

Last year, hundreds of immigrants from Egypt, Somalia, Pakistan, Iran and Syria who were caught entering the U.S. were able to stay in the country by saying those magic words.

“Dangerous criminals and potential terrorists are gaming the system without consequence,” DeSantis said. “These numbers illustrate vulnerabilities throughout our immigration system.”

We could probably tighten that up pretty quickly. But first we need a president who thinks it’s a problem.