Brussels joined the list of places Wednesday where U.S. troops can't go without a general's approval and the advice from the command on what to do if caught up in an attack came down to this: "Run, hide and then fight if necessary."
The warnings came after an Air Force lieutenant colonel and four members of his family were injured in the nail-laden bomb attacks Tuesday on Brussels' Zaventem international airport and at the Maelbeek stop on the Brussels subway near the U.S. embassy and the headquarters of the European Union.
Air Force spokesmen said they could not immediately give an update on the conditions of the officer and his family members due to privacy reasons but initial reports said the injuries don't appear to be life-threatening. The service said that the officer was assigned to Joint Force Command Brunssum, a NATO command in the Netherlands which provides support to the mission in Afghanistan.
Tuesday's attacks claimed by the Islamic State of Iraq and Syria, or ISIS, killed at least 31 and wounded more than 260, according to Belgian Federal Prosecutor Frederic Van Leeuw, but he warned that the list of casualties could grow.
Addressing the Corps of Cadets at the U.S. Military Academy at West Point Wednesday, Defense Secretary Ashton Carter said that the Brussels attacks and the injuries to the Air Force family would not deter the U.S. from its commitment to destroy ISIS.
The terror bombings were "a grim reminder of how serious are the dangers we face, the dangers civilization and our country face," said Carter, who cited "the military family that was affected by these attacks."
Carter said the Pentagon will "do everything we can" to protect the Air Force family injured in Brussels and all military families against future attacks. He added that "no attack, no attack, will shake our resolve to accelerate" the campaign to defeat the extremist group.
All the service branches, the Defense Department and the State Department renewed and tightened travel restrictions and warnings on the ISIS threat throughout Europe and in Turkey for U.S. citizens and the more than 60,000 U.S. military personnel in Europe, with special emphasis on the upcoming Easter holyday weekend.
"The recent attacks that we have seen in Brussels and Turkey really highlight that we are facing a significant and persistent threat throughout the theater," said Robert Balcerzak, deputy chief for anti-terrorism for U.S. Army Europe.
The response of troops caught up in a terror attack "really depends on the situation," Balcerzak said in a statement. "In the event of an active shooter, the DoD stresses to run, hide and then fight if necessary. Perhaps most important -- if host nation or U.S. security is responding, be very cooperative with the law enforcement and careful you do not make yourself a suspect."
Shortly after the Tuesday attacks, U.S. European Command put an indefinite ban in effect on travel by military personnel to Brussels "as a precautionary measure to keep personnel and families safe."
"Specifically, unofficial travel to Brussels (leave, liberty, and special pass) is prohibited until further notice," the command said. "Those on official travel or emergency leave to Brussels will also require the approval of the first General/Flag Officer in the traveler or sponsor's chain of command." Similar restrictions were already in effect for travel to Turkey.
For those personnel assigned to NATO headquarters at Mons south of Brussels, the latest restrictions came on top of increased security that was already in place following the terror attacks in Paris last November.
One family member told Military.com that stronger gate security, altered access points and added security patrols are visible, but otherwise "life is going on as usual." Other changes have also been put in place, she said, such as a decision to move both an annual school prom, traditionally held in a nearby chateau, to the base club as well as the annual high school graduation ceremony.
Periodic travel restrictions have become the norm for military personnel in Europe in recent years to lower the risk posed by terrorism following incidents in which U.S. personnel were targeted or found themselves caught up in a terrorist act.
In 2011, an attack on a group of Airmen at the Frankfurt airport in Germany killed two troops, and last August an off-duty airman traveling by train to Paris was credited with the help of two friends with subduing a gunman.
Lt. Gen. Ben Hodges, the USAREUR commander, said, "The reality of these attacks highlights the need for us all to be vigilant. I urge everyone to be aware of their local security situation, listen to AFN [Armed Forces Network] or local news outlets and ensure you are signed up for [the emergency communications system] AtHoc with your local garrison so that you may have the latest updates.
"If you see something that you think is suspicious, there are many different vehicles you can use to report," Hodges said. "iReport is a downloadable app that you can get on your smartphone which would make a quick way to report any suspicious activity, or you can go online to any one of the USAREUR webpages to iWatch -- it's the same mechanism."
The travel alert put out to all U.S. citizens by the State Department after the Brussels attacks warned of the "potential risks of travel to and throughout Europe."
It said, "Terrorist groups continue to plan near-term attacks throughout Europe, targeting sporting events, tourist sites, restaurants, and transportation. U.S. citizens should exercise vigilance when in public places or using mass transportation."
In addition to avoiding crowded places, U.S. citizens should "exercise particular caution during religious holidays and at large festivals or events," the alert said.
-- Richard Sisk can be reached at Richard.Sisk@Military.com.
-- Amy Bushatz can be reached at firstname.lastname@example.org.