The full force of federal law was brought to bear yesterday on an illegal structure in Lafayette Park: an igloo.

According to U.S. Park Police, two men were arrested at 1:30 p.m. after resisting efforts by park police to tear down the seven-foot-tall igloo they had built in the park's southeast corner, near Jackson Place and Pennsylvania Avenue, across the street from the White House.

After their arrests, the offending structure was reduced to a shapeless foot-high mound of snow and ice, police said.

The men were identified as Robert Allen Darrough, 27, of 1440 N St. NW, and Andrew Neal Hammerman, 20, whose address was unknown. According to police, Darrough regularly posts a sign in the park that says, "Give Peace a Chance."

The two were busily building their snow palace with a hoe and milk cartons when Park Police Officer Bradley Hewick ordered them to stop, police said. Hewick cited National Park Service regulations enacted in April that prohibit structures taller than four feet, said Lt. William Hall. The regulations are designed to prevent unsightly protest signs in front of the White House.

However, the two refused to tear down the igloo, Hall said.

After Hewick took the hoe and began to hack away at the igloo, one of the men tried to grab the implement, police said. Hewick handcuffed him and then returned to his assault on the igloo. The other man took a different tack, using his milk carton to pour back snow on the igloo as Hewick chipped away at it, police said.

The two men were arrested on misdemeanor charges of violating the park's structure regulations, impeding the duties of a police officer, and disorderly conduct, Hall said. They were taken to Park Police headquarters and charged yesterday afternoon and awaited a hearing before a U.S. magistrate.

The igloo was illegal not only because of its size, but because it was an enclosed structure that could pose a threat to the White House, Hall said. "If you have something that can conceal a large charge, or a missile launcher, that is definitely a problem," Hall said.

Asked if a five-foot-tall snowman would violate park regulations, Hall said, "That would depend on the snowman. If the snowman would allow you to conceal potential problems, then it would have to come down. If it was just your basic snowman where you could see around, then it would be open to interpretation."