So are we safer now, a decade after the terrorist strikes that killed more than 3,000 Americans on Sept. 11?

Yes, thanks to everyone who works - day in and day out - to keep us safe and secure. But there’s considerable room for improvement.

Law enforcement officials have become much better at sharing information and linking databases. They’ve thwarted at least 40 post-Sept. 11 attacks, thanks largely to security changes made in the wake of that devastating day. That’s the good news.

But we have to guard against the danger of complacency. Yes, it’s good that we’ve stopped these attacks before they could be launched. But the fact that there have been so many attacks to stop is bad news. It’s obvious that America’s enemies are determined to bring this country down.

That’s why we must be even more determined to stop them.

How we can do that is the subject of a new report from the Heritage Foundation, “Homeland Security 4.0.” It contains a checklist with 35 critical steps that federal policymakers can take to make us more secure. Among them:

- Stop interfering with state and local efforts to battle illegal immigration. Security starts with something pretty basic: whom you let in - and whom you allow to remain. More than 10 million illegal immigrants are inside the United States. A sizable number entered with valid visas but stayed after their visas expired. Yet the federal government discourages state and local governments from enforcing immigration laws.

Ask Arizona. Last year, it enacted a law that allows law enforcement officers to ask a person who has been stopped, detained or arrested about his legal status if officers have a reasonable suspicion that the person is unlawfully present in the United States. Those of us here legally often have to provide a driver’s license and registration at a traffic stop, so this hardly seems like an unreasonable request.

Did the Obama administration appreciate the extra hand Arizona was providing in enforcing immigration policy? After all, fewer than 6,000 federal Immigration and Customs Enforcement agents patrol our borders. But no - the administration responded by suing Arizona. This is perverse. State and local officials know better than Washington what threats they face; they shouldn’t be harassed for taking reasonable efforts to secure their own borders.

- Preserve existing counterterrorism tools, including the Patriot Act. In the immediate aftermath of Sept. 11, the conventional wisdom was that the next terrorist attack on the U.S. homeland was a matter of “when,” not “if.” Yet that hasn’t happened. Why? A great deal of credit goes to effective counterterrorism measures such as the Patriot Act, which has played a large role in foiling the 40 plots mentioned above.

You can bet our enemies have at least another 40 plots in the works. National security investigators need the authority provided by the Patriot Act to track leads and derail attacks before the public is put in danger.

Fears that the act would be misused have proved overblown. Besides, Congress has extensively modified it over the years to incorporate significant new safeguards, including substantial court oversight. Congress should not let the provisions expire and should make the authorities permanent.

- Privatize airport security. Almost no one likes the way the Transportation Safety Administration handles its mission of providing airport security. Treating every person and package as an equal risk is absurd - and a waste of resources. Congress needs to change TSA’s mission to making aviation security policy and shift its screening responsibility to the airport level under the supervision of a federal security director.

The TSA then could develop a modern international passenger and cargo security system - one that relies on “focused security” by targeting the most resources against those who pose the greatest risks.

We’re safer today - not by luck, but because of concrete steps we took to improve our security. We can’t afford to let the job remain unfinished.

Ed Feulner is president of the Heritage Foundation.