Wednesday morning, a K-9 unit found a suspicious package at Kennedy Airport. The bomb squad was contacted. Terminal 5 was evacuated. Roads were shut down.

It’s happened before. But people saw this incident differently, as it came a day after 41 people were killed and hundreds injured in a suicide attack at Ataturk Airport in Istanbul. At Kennedy, the package was harmless. An hour later, the terminal reopened, and normal activity resumed.

Normal. The word takes on new meaning with every attack like the one in Istanbul, which came three months after suicide bombers killed 16 at the Brussels airport.

On Wednesday, normal included stepped-up patrols, some heavily armed, at all three NYC-area airports, augmenting counterterrorism forces still in place since the June 12 nightclub shooting in Florida. The extra presence is partially to make us feel safer, but high levels of security can only help in the effort to find and stop potential threats. That ramp-up may have to become more constant.

Normal now means there’s always a focus on intelligence, on understanding risks and threats. Yet, even when officials are aware of the potential for an airport attack, as they reportedly were in Turkey, it’s still so hard to stop, whether the Islamic State group, a lone wolf or something else is responsible. And normal means there’s a regular drumbeat of concern. Let’s face it; no matter what, our airports, as economic and travel centers and gateways to the world, and other key hubs, are always under threat.

Our reaction is always to seek more security, to try to prevent attacks. The Brussels and Istanbul bombings both occurred outside of security checkpoints. Some suggest moving airport security operations. But where? To entrances? To roadways outside? To highway exits? Should we close the Van Wyck Expressway? And won’t the bombers just adjust to any changes we make? There aren’t easy answers, just hard questions. No matter the answers, there will be spots of vulnerability. As we embark on a summer that will, for some, include air travel, we should stay vigilant, even concerned. Yet, we travel. We live normally, even as the meaning continues to change.