Within a couple of hours of the news of the killing of Osama bin Laden by US special forces on Monday morning, two messages arrived. One was from the Foreign Office, warning of the danger of reprisals from followers of the man who made a speciality of the mass-production of misery: his death "may lead to an increase in violence and terrorist activity". The other was from a reader concerned about her imminent trip to New York:
"I am flying to the US on Wednesday. Now with the death of Bin Laden I am concerned about flying to the States and and then flying back again. Should I cancel?"
Because of her imminent departure, I phoned to seek to persuade her to go ahead with the trip, and I hope I succeeded.
You may also be concerned about the latest twist in the world order and how it could affect transatlantic travellers. After all, Bin Laden was the man who used civil aircraft as weapons for a massacre, and his followers have repeatedly targeted tourists. So let me suggest strategies that may help minimise the risk of being caught up in the retribution that various extremist websites are threatening.
First, travel right now. If the middle-managers of what remains of the al-Qa'ida franchise are plotting to wreak revenge on the West, experience shows that most attacks take months to prepare. Yet security between the UK and US has already been stepped up, judging from what the Secretary of Homeland Security, Janet Napolitano, called "an evolving threat picture both in the coming days and beyond".
Next, consider your choice of airlines. The most notable attacks in the past decade have targeted the three biggest US carriers: United (on 9/11), American (on 9/11, and a few months later by the "shoe bomber", Richard Reid) and Delta (whose flight from Amsterdam to Detroit on Christmas Day 2009 was threatened by the "underwear bomber", Umar Abdulmutallab).
I would happily fly on any of these three excellent airlines tomorrow. But I would not be surprised if some prospective passengers were to consider other carriers to be less of a risk.
UK airlines have an amazing safety record, with no fatal crashes involving passenger jets since 1989. But Britain also has what the Foreign Secretary this week called an "indispensable relationship with the United States", and we share responsibility with America for the invasion of Iraq in 2003. The weapons of mass destruction that provided the Allies' justification proved illusory, but the invasion has unleashed hatred – which could, I fear, be aimed at travellers.
Anyone planning to fly non-stop from Heathrow to Los Angeles has plenty of choice, with five airlines competing. Of these, it is difficult to imagine that Air New Zealand's daily flight NZ1 constitutes as tempting a target as the UK and US operators.
To other American destinations, you could decide that a connecting flight with a "neutral" airline such as Aer Lingus or Icelandair is less likely to attract the attention of would-be murderers than a British or American carrier. Yet a converse argument maintains that UK and US airlines will henceforth be even more obsessed with safety and security than their rivals, and therefore a better bet.
Travelling around the US? This is the day of the train
As President Obama eloquently said, the most tragic consequences of the 9/11 attacks "go unseen to the world", symbolised by "The empty seat at the dinner table".
Those of us fortunate enough not to have been directly touched by terrorism are aware that travel, particularly aviation, has changed as a result of the wicked work of Osama bin Laden.
Aircraft comprise terrorists' target of choice because of the potential for mass casualties and making headlines. So security checks have got ever more invasive.
Rail provides the ideal alternative for travelling around the US. Today is National Train Day in America, with events from New York's Penn Station to Los Angeles Union.
Book well in advance at amtrak.com, and a one-way ticket from coast to coast costs only $197 (£130). The three-day trip includes a free afternoon between trains in Washington DC; much of the next day in Chicago; and an amazing daylight journey from Dodge City in Kansas across the Rockies to Flagstaff, Arizona.
Reawakening the joy of travel comes free.