JIDDA, Saudi Arabia — Traveling in an armored convoy under heavy security, Secretary of State James A. Baker III made a surprise visit to Lebanon on Thursday in an effort to dramatize the country's increasing stability and its recovery from more than 15 years of bloody civil war and anarchy.

Led by army vehicles and a mounted 7.62-millimeter machine gun, with Syrian intelligence and security officers joining American escorts in the motorcade, the secretary of state crossed at midday from Damascus across the Lebanese border into the Bekaa Valley, the area from which terrorist groups have launched a series of bombings and kidnapings of Americans and other Westerners.

So intense was the security that during Baker's return to Damascus, after news of his presence inside Lebanon had spread and thus increased the potential danger, his official convoy was preceded by an entire 12-car "dummy" motorcade. The fake convoy, which even included an ambulance, was designed to divert any potential attackers.

Baker's trip was the highest-level American visit to Lebanon since then-Vice President George Bush came in October, 1983, days after 241 U.S. servicemen were killed in a car-bomb attack in Beirut.

The terror-filled days of the mid- and late 1980s followed. In those years, the Reagan and Bush administrations were preoccupied with efforts to free the Americans taken hostage by terrorist groups in Lebanon, such as the Hezbollah militia. Many of the hostages were held in the same region through which Baker traveled Thursday.

"I have to tell you, I never felt that I would be coming to the Bekaa Valley, having been in the United States government in one form or another for the past 12 years," Baker told a press conference held at the country home of Lebanese President Elias Hrawi in the town of Zahlah, 33 miles from Beirut. "I do believe that it's an indication of the extent to which the United States supports the political independence and sovereignty of Lebanon."

Lebanese officials, who had been urging an American visit to help dramatize Lebanon's recovery, were clearly thrilled. "Lebanon has lived a painful 16 years, and . . . you are witnessing Lebanon's way out from the misery of war," Hrawi told the secretary of state. Lebanon's civil war erupted in 1975 and raged intermittently until peace was imposed last year with the help of Syria, the dominant foreign power in Lebanon.