BOGOTA, COLOMBIA, AUG. 7 -- Cesar Gaviria Trujillo assumed the presidency today under tight security, vowing to coordinate personally the fight against cocaine terrorism but demanding greater international efforts to control the consumption of cocaine, money laundering and arms smuggling.

The 43-year-old economist of the Liberal Party was inaugurated at a ceremony in a small plaza outside the Narino Palace, with 1,200 guests from 87 countries, including five heads of state and Vice President Dan Quayle. Gaviria, the heads of state and Quayle sat on a raised platform surrounded by bullet-proof glass.

Sharpshooters lined the surrounding rooftops. Thousands of troops, along with tanks and armored personnel carriers patrolled the streets, and helicopters buzzed overhead.

"Narco-terrorism today is the principal threat to our democracy, and we will face it without making concessions," Gaviria said in his inaugural address. "There is no other way to eradicate from Colombian life the assassinations, the hundreds of dead from car bombs . . . and the police gunned down on the streets of Medellin."

"Because leadership of this struggle cannot be delegated, the president of the republic will lead the actions . . . to defeat the terrorists and end these barbaric acts," said Gaviria, whose term runs four years. "The job of strengthening our intelligence and having true leadership in this field cannot be delayed, and will be carried out under my personal direction."

Three presidential candidates were killed during the campaign, allegedly by the Medellin cocaine cartel.

Gaviria takes over from fellow Liberal Virgilio Barco, who won praise for his strong stand against cocaine traffickers, including the use of extradition, a policy Gaviria said he would continue until Colombia's justice system is strengthened through his proposed programs of special tribunals of anonymous judges and high-security prisons to handle terrorists.

"Extradition cannot be the only, or principal instrument in fighting drug trafficking," Gaviria warned. "It is a tool to be used at the discretion of the executive branch."

"While narco-terrorism is our problem, drug trafficking is an international phenomenon that can only be dealt with by joint actions of the affected nations," Gaviria said. "We expect more of industrialized nations, not just against consumption, but with tighter controls over money laundering, arms trafficking, distribution networks, precursor chemicals and coca leaf production."

Earlier in the day, Gaviria met with Quayle for an hour and reiterated his government's desire to maintain good relations with the United States.

Gaviria has chastised the United States for maintaining trade barriers against Colombia and said more trade, not economic or military aid, was what the country needed.

In a press conference after the meeting, Quayle said he had come "to show the strong importance that the United States places on continuing our partnership with Colombia."

Quayle said he had agreed to bilateral trade initiatives and said talks on implementation will begin no later than the first week of September.

Gaviria, who served as Barco's minister of finance and minister of interior, entered the race following the assassination of leading Liberal candidate Luis Carlos Galan, his political mentor.

He won only 48 percent of the vote in the May 27 elections, but he has generated high expectations among Colombians tired of the violence and eager for change. A poll of 1,981 people released by the El Espectador newspaper today showed that 85 percent were "optimistic" about the Gaviria government, and only 15 percent were pessimistic.

Gaviria's youth and well-known love of rock music, his 34-year-old wife and two small children, and the fact that most of his closest advisers are under 30 have served to mark this inauguration as a change of generations in Colombian politics.

Hoping to build a national consensus, Gaviria included four parties in his cabinet, including former M-19 guerrilla commander Antonio Navarro Wolf, who ran third in the presidential elections, as minister of health.