THE LATEST reports indicate that Colombia's war on the drug trade may be faltering.

This is ominous: Colombia is the funnel of most South American cocaine that flows to the United States and Europe. Spurred by the assassination of its minister of justice, it conducted in 1984 a prodigious anti-trafficker campaign, losing 140 policemen to gunmen and starting to extradite major suspects to the United States -- drug-bought corruption immunizes them from prosecution at home. Yet The Post's Jackson Diehl reports that a fugitive trafficking suspect has just proclaimed his defiance of Colombian law on local television, and identified coca planting as a patriotic protest against "American imperialism." A new House Foreign Affairs Committee study concludes about Colombia that it has "not yet demonstrated a serious resolve to confront the major traffickers."

Certainly Colombia and other countries involved in the drug trade have a heavy responsibility. The burden on them is not of their own making: It results from the immense demand for drugs generated primarily by the American market. Still, neither the source of their discomfort nor the difficulty of the task relieves them of the obligation to enforce the law vigorously.

At the same time, as the House Foreign Affairs study, "U.S. Narcotics Control Programs Overseas: An Assessment," makes clear, the United States is itself laggard. The study's first general recommendation goes right to the point: "The United States should better demonstrate its own commitment to the fight against narcotics, including spraying domestically the herbicides it urges other countries to use on illicit crops, increasing asset seizures and wiretaps, devoting adequate resources to the agencies involved in anti-narcotics work, and prosecuting narcotics offenders to the fullst extent of the law."

The matter of resources is a litmus issue. Some aspects of enforcement are bound to come hard. For instance, the American system does not make it easy to ensure tough sentences for the big offenders. But why is there "a lack of coordination between responsible U.S. Government agencies, poor program management, and a lack of support from U.S. agencies' headquarters in Washington for their front-line officer in the field"? Why are there only an "obviously inadequate" 16 Drug Enforcement Administration agents in Colombia? Why do they lack secure telephones? Why have there been no recent aerial surveys in the four big producing countries "despite repeated requests from U.S. Embassies"? How long will the State Department countenance a situation where "narcotics assignments are viewed with distaste from a career standpoint"? For these lapses, there can be no excuses. The war on drugs begins at home.