The US president is the most protected person on the face of the planet, and when he travels, his protectors must make sure the security blanket goes with him.
The effort comes into sharp focus today, as Secret Service agents accompany President Clinton on a 24-hour visit to Greece - which experts say ranks among the most dangerous in the history of presidential trips.
In the modern era, ensuring presidential security abroad has become ever more costly and sophisticated, involving everything from airlifting armor-plated "war wagons" to welding manhole covers along routes the chief executive will travel.
The Secret Service might wish the president was confined to home turf, since the White House complex is arguably the safest seven acres on earth. Yet the demands of presidential leadership - and in this case the desire of Mr. Clinton to foster peace on the Greek/Turkish island of Cyprus - often push presidents outside that security cocoon.
"Greece is of particular concern," says Neil Livingston, who heads GlobalOptions, a security firm in Washington. "Greece has the worst [security] record in Europe, it has abysmal policing." And any number of groups have "made it clear they'd love to target Clinton."
From suspected Muslim terrorist Osama bin Laden to thousands of Greek nationals furious over US policy in the Balkans, the burden on the US Secret Service to protect the president abroad has been amplified.
In fact, the White House postponed original travel plans to Greece, once scheduled for Nov. 13 to 19, and cut the visit to a single day.
Yet, if the president is out of his protective cocoon, the Secret Service maintains he still has the same degree of protection.
"We recreate the security" of the US, says Chaun Yount of the Secret Service. "It's just different working conditions."
Different indeed. The Pentagon airlifts armored limousines and war wagons - the smoke-windowed GM Suburbans that bristle with armaments and agents - as well as secure communications vehicles.
When Clinton visited Africa, 98 military airlifts helped deliver such equipment, and 13 presidential helicopters were deemed a necessary redundancy for evacuation in case the president was wounded or hurt.
Such precautions, while growing in scale, are nothing new. Costa Ricans are said to have been amused when President Ronald Reagan showed up there in 1982 with a C-5 cargo plane in tow, carrying three armored Lincoln Continental limos.
In advance of any overseas trip, security teams map out routes and go over schedules, creating detailed operational plans weeks, even months, ahead. The Secret Service office in Rome has been a hub of coordination for the current trip.
"The preparations include building sweeps, searching for explosives, even welding manhole covers," says Bob Taubert, a former FBI counterterrorism expert, now head of the Center for Security Studies and Applications Inc.
The Secret Service depends to a degree on the host country's security infrastructure. In Turkey for example, where the president spent most of this week, more than 35,000 police and paramilitary forces combed the streets of Istanbul Wednesday, with an eye out for radical left-wing groups.
Security has been ramped up in Athens in the days preceding Clinton's visit. In perhaps the most severe restrictions on protests since military rule ended 25 years ago, the government has imposed a ban on demonstrations on the route from the airport. In addition to other threats, this week marks the anniversary of a student revolt crushed by the military junta in 1973.
Politically, curtailing and postponing a trip to Greece has few consequences at home.
"But for American policy interests, it gives a bad impression of the host country that we don't trust it or that they don't have good security," says Paul Quirk, a political scientist at the University of Illinois at Urbana-Champaign.
If schedule switches are unusual, Secret Service nail-biting is not. "There is a long history of security concerns and of presidents going into dangerous places," says George Edwards, director of the Center for Presidential Studies at Texas A&M University in College Station.
Franklin D. Roosevelt crossed the Atlantic in wartime to meet with British Prime Minister Winston Churchill.
Vice President Richard Nixon and his wife Pat confronted a spitting, rock-throwing mob on the streets of Caracas, Venezuela - an event that shook Mr. Nixon and stayed with him his entire life.
Clinton, too, has had moments of anxiety during 45 trips to 63 countries. During his Africa trip last year, while addressing a packed stadium amid triple-digit temperatures, the crowd began pressing toward the fence to shake hands with him.
An angry, disturbed president yelled at the crowd to move back as those nearest the barricades were crushed in front of Clinton. The Secret Service insists the president was never in danger.
(c) Copyright 1999. The Christian Science Publishing Society