The Plastics Recycling Show (PRS) Europe, a two-day conference for members of the plastics and recycling industries, has been cancelled after an official warning put Brussels on the highest level of terror alert this weekend. The Belgian government raised the threat alert in the region to level four—"serious and immediate threat"—following investigations into the recent terrorist attacks in Paris.

Crain Communications, which organizes the event, released a statement saying that "a decision will be made at a later date regarding when will be a suitable time for the event to take place." The conference was scheduled for Wednesday and Thursday (November 25 and 26) at the Tour & Taxis Venue in the Belgian capital.

Brussels has been locked down since Saturday, with armed police and troops patrolling the almost deserted streets. The Plastics Recycling Show show is just one of the many events that have been postponed or called off altogether under the current terror lockdown, which, authorities say, could continue for another week due to the ongoing terrorism threat. Possible targets were "malls, shops and public transport," said Belgian Prime Minister Charles Michel.

Meanwhile, a manhunt is in full swing following the November 13 attacks in Paris for a Belgian national named Salah Abdeslam, one of the terrorists involved in the attacks, who is still at large. Launched by French and Belgian authorities, German police in the North Rhine-Westphalia region that borders Belgium have now also joined the hunt.

Nonetheless, the prime minister has said that the city's schools and subway will re-open on Wednesday, somewhat to the consternation of many parents who would prefer to see Salah Abdeslam caught first. However, the government also said it is bringing in police from outside Brussels to provide extra security for the schools.

Security has been tightened across the entire continent, not just in France and Belgium. Several soccer games have already been postponed, stringent border controls are being implemented, a number of countries have raised their threat alert levels and quietly beefed up patrols at public sites and embassies. Perhaps most disconcerting, however, is the increased police presence everywhere and the images of troops guarding Brussels with loaded guns. As one Brussels resident said: "Surreal doesn't begin to describe it."

For its part, the U.S. State Department has issued a worldwide travel alert, exhorting U.S. citizens to "exercise vigilance when in public places or using transportation. Be aware of immediate surroundings and avoid large crowds or crowded places. Exercise particular caution during the holiday season and at holiday festivals or events." 

The department also wrote that current information suggests that ISIL (aka ISIS and Da'esh), al-Qaeda, Boko Haram and other terrorist groups continue to plan terrorist attacks in multiple regions.