Constantine Menges, 64, a national security aide for Latin America during the Reagan administration who had a central role in planning the U.S. invasion of Grenada in 1983, and who focused on the continuing threat of communism in books and numerous articles, died of cancer July 11 at Sibley Memorial Hospital. He lived in the District.

At the time of his death, Dr. Menges was a senior fellow at the Hudson Institute, a public policy think tank. His recent work had focused on the threat to the United States of a growing pro-Castro alliance throughout Latin America; state-sponsored terrorism, including what he considered Iran's subversion of Iraq; and the rise of China as a superpower.

Dr. Menges had just completed the manuscript for a book titled "China, the Gathering Threat: The Strategic Challenge of China and Russia." He also was the author of a memoir, "Inside the National Security Council," several other books, and numerous articles.

Dr. Menges was born in Ankara, Turkey, the son of political refugees from Nazi Germany. The Menges family, fearing that Turkey would enter the war as an ally of the Axis powers, moved from place to place through war-torn Europe. The family arrived in the United States in 1943.

Dr. Menges received a bachelor's degree in physics from Columbia College and a doctorate in political science from Columbia University. He taught political science at the University of Wisconsin before joining the Rand Corp.

He entered government service in the late 1970s, first as assistant director for civil rights, then as deputy assistant secretary for education in the Department of Health, Education and Welfare.

From 1981 to 1983, he was a national intelligence officer for Latin American affairs at the Central Intelligence Agency under Director William Casey. From 1983 to 1986, he worked for the National Security Council as a special assistant to the president, specializing in Latin America.

In "President Reagan: The Role of a Lifetime," author Lou Cannon described Dr. Menges as one of a cadre of National Security Council aides who believed, as did Casey, "that the West should be mobilized to fight Communists with their own methods."

Cannon described Dr. Menges "as one of the most forceful of these polemicists" and "a principled conservative." White House and State Department pragmatists, according to Cannon, dubbed him "Constant Menace," a play on his name, for his ardent support of action, covert and otherwise, against Nicaraguan Sandinistas and Salvadoran rebels.

Deeply involved in White House support for the Nicaraguan contras, Dr. Menges also argued that an American strategy for combating communism in Latin America should include suppression of right-wing death squads and promotion of land reform.

"He believed that the United States should compete with the Soviets in sponsorship of 'national liberation movements' in Third World nations," Cannon wrote.

Dr. Menges contended that the invasion of Grenada helped avert a possible Grenada nuclear deployment crisis and strengthened President Ronald Reagan's hand in deploying intermediate-range missiles in Europe in late 1983.

From 1990 to 2000, Dr. Menges was a professor at George Washington University, where he founded and directed the Program on Transitions to Democracy. His work on democratic transitions included the post-communist states, Iraq, Iran and the Americas. He also began a project on U.S. relations with Russia and China and the new Russia-China alignment.

In articles that appeared regularly in The Washington Post, the Washington Times, the New York Times, the New Republic and other publications, Dr. Menges continued to warn that the communist threat persisted.

In a Washington Post opinion article in 2001, he wrote that "Russia and China are using mostly political and covert means to oppose the United States on security issues and to divide America from its allies."

As a college student, Dr. Menges helped individuals escape communist East Berlin in 1961, and in 1963, he worked in Mississippi as a volunteer for equal voting rights.

Survivors include his wife of 29 years, Nancy Menges, and a son, Christopher, both of Washington.

Constantine Menges also worked at the CIA and the Hudson Institute.