Ignatius Ndefru Nkwenti, an African diplomat newly arrived in the United States, did not understand the meaning of the burning cross on the lawn of his Silver Spring home, but he guessed enough to be afraid.

Nkwenti, a 36-year-old cultural attache from Cameroon, was asleep with his wife and four children in their rented house Wednesday night when a 12-foot wooden cross was planted in the lawn and set afire shortly after 11 p.m.

The family, who came to the United States 10 days ago, did not realize what was happening until they were awakened by police summoned by a neighbor.

"Why should people try to frighten me?" Nkwenti asked yesterday. "I was very upset. I am a stranger. I just moved to this house. In my country, we welcome strangers more than our own citizens."

Nkwenti said police had explained the antiblack message traditionally associated with cross-burnings and had told him about "movements here who do that to scare people." When informed yesterday about the existence and activities of the Ku Klux Klan, Nkwenti asked if the group might harm him or his family. He wondered if the incident took place on one of the group's "special days," or holidays.

Montgomery County police said they had no witnesses to the cross burning and no suspects and that the incident was under investigation.

Three of Nkwenti's children slept through the cross-burning, he said, and he decided not to tell them about it because he did not want them "to panic." He said he "felt horrible" and was so afraid that he left the lights on in his house for the rest of the night.

But he said he and his family intend to remain in their house despite the incident.

Montgomery County police spokesman Nancy Moses said the cross was constructed from two-by-four planks of plywood held together with wire. It stood on the lawn to one side of the house on Grove Street, just 25 feet from an American flag flying from a pole in the yard next door.

The cross-burning in Silver Spring is only one of a number of incidents involving racial or religious hostility in Montgomery County, where the minority population has doubled in the last decade.

Although there have been arson attempts in Nkwenti's neighborhood, neighbors said the cross-burning was the first serious racially motivated incident in their predominantly white, middle-class section of Silver Spring.

The Nkwenti family was the only black family on the quiet street, although another black family has lived around the corner for three years.

One neighbor, Edward Nickolaus, who first spotted the burning cross when he and his wife returned home from dinner, said Nkwenti and his family were "very nice and very quiet."

"I feel sorry for them," Nickolaus said. "I said to my wife this morning, 'What's going to happen next?' "

Nkwenti rented the house from a Nigerian named Isaac Making, who, neighbors said, bought it in August from a white couple that moved to Florida.

"There are some people around here who don't like blacks," said D. A. Knupp, a District police officer who has lived for three years in the house next door to Nkwenti's home. Knupp said some residents used racial epithets and said they hoped the house would not be sold to blacks.

Knupp said some residents were "shocked" when they learned that the previous owners of the house were dealing with a black real estate agent. It was that agent who arranged the sale to Making.

After buying the house Making made it known to his neighbors that he wanted to rent to black Africans and not to American blacks, Knupp said.

Some neighbors said white residents were upset because blacks have moved into two high-rise apartment buildings on the commercial strip of Georgia Avenue just a few blocks away and travel through the neighborhood.

Cross-burning is a felony under Maryland law.