But his presence and growing U.S. military aid to the war-torn country appear to enjoy broad support here, despite the traditional sensitivity about U.S. involvement in Latin America.
Policies such as the long-standing U.S. trade embargo against Cuba, the 1989 U.S. invasion of Panama and Washington's support for Nicaraguan rebels and the Salvadoran military during the 1980s have bred resentment in the region.
But in a Gallup poll published over the weekend, 56 percent of Colombians said they would support direct U.S. military intervention to resolve their country's 36-year guerrilla conflict. Forty percent said they were opposed to such an action, in the telephone survey with a 5 percent margin of error.
Another poll published Tuesday in El Espectador newspaper found 74 percent of Colombians approve of Clinton's visit, and just 20 percent oppose it. The poll had a 2.4 percent error margin.
``Colombia can't wipe out its drug trafficking problem by itself. We need help, and I personally welcome the aid from the United States,'' said Mauricio Lopez, a businessman, as he ate at a McDonald's in an upscale Bogota neighborhood.
People waved Colombian and U.S. flags and cheered Clinton's motorcade Wednesday as it wound through the cobblestone streets of the Caribbean port of Cartagena, the site of the one-day stop.
But Colombians opposed to a $1.3 billion aid package for the South American country _ largely for helicopters and troop training _ were also out in force.
In Bogota, at least 2,000 labor unionists and students marched from the National University to the U.S. embassy, chanting anti-Clinton slogans and burning American flags and effigies of Pastrana and Clinton. Ski-masked students torched a bus, and a riot police officer died after being struck in the head by a homemade grenade thrown from the crowd.
The anti-drug aid package ``violates our national sovereignty,'' said Pablo, a 20-year-old student leader. The real goal of U.S. policy is to squash the rebels and enforce economic policies that favor multinational business at the expense of the poor, Pablo claimed.
Protesters also burned American flags in Medellin and Cali, Colombia's second-and-third largest cities. In Cartagena, police scuffled with protesters outside the convention center serving the foreign press and arrested four of them. One demonstrator had been shouted into a megaphone: ``Go home Clinton, violator of human rights.''
The guerrillas also made their feelings known with scattered attacks apparently timed to mar Clinton's visit.
Police blamed the Revolutionary Armed Forces of Colombia, or FARC, for a small bomb discovered in a Cartagena neighborhood hours before Clinton was scheduled to appear there Wednesday.
Carlos Perdomo, spokesman for the National Police, said the bomb was apparently intended to spread propaganda leaflets, not cause injuries. Two FARC members seen planting the device were arrested, eastern Arauca state accidentally exploded.
On Tuesday, FARC set off small bombs, skirmished with troops and shot at rural police stations in seven of the country's 32 states _ killing two officers and at least seven civilians.
While opposing growing military ties between the United States and Colombia, even the rebels insist they have nothing against the American people.
``What we oppose are the imperial policies of the United States government,'' a bearded FARC rebel leader, Alfonso Cano, told The Associated Press in southern Colombia last week.