Today, I received a copy of an advisory which the staff of P&O’s Britannia distributed to passengers aboard the cruise ship, prior to disembarking in Bruges, advising them of the existence of a possible threat associated with "extremist activity in Belgium."  

The advisory of today’s date, from the master of the cruise ship, says in pertinent part:

"As your safety and security is always of prime concern to us on-board Britannia, I would like to advise you of the existence of a possible threat associated with extremist activity in Belgium.  While it is not our wish to concern you, due to recent events, it would be similarly irresponsible of us not to make you aware of localised security concerns.

We would like to remind you to remain vigilant in all public areas, avoid demonstrations and report anything suspicious to the local authorities.

If you are planning to travel to Brussels independently, we would recommend that you are particularly alert in places where there is a high concentration of people."  

The cruise line advisory mirrors the official U.K. advice for Belgium, which states:

"There is a high threat from terrorism and the Belgians assess this to be a serious and real threat (level 3). Police operations are ongoing and there have been a number of police raids and arrests, including on 17 June 2016, relating to past and potential terrorist attacks.

There have been a number of high profile terrorist attacks across Belgium. On 6 August 2016, 2 police officers were attacked with a machete in the city of Charleroi. On 22 March 2016 co-ordinated terrorist attacks killed 32 and injured hundreds more at Brussels Zavantem airport and on the metro system."  

The UK advisory is similar to the U.S. travel statement which states that another terrorist attack is "probable." 

This Britannia advisory seems like a prudent warning in this day and age.  The Britannia is now sailing back to Southampton after a day in Bruges.