In a May 20 letter to President Alvaro Uribe, Inspector General Edgardo Maya argued that the 1974 diplomatic agreement that protects US soldiers from Colombian justice is invalid because it violates the Constitution.

In the past three months, seven American soldiers have been arrested in two separate incidents involving arms smuggling and drug trafficking. At the start of May, Army Warrant Officer Allan Tanquary and Sgt. Jesus Hernandez were arrested near the Tolemaida military base with nearly 40,000 rounds of ammunition that were allegedly intended for right-wing paramilitaries. At the end of March, five US soldiers were detained for allegedly smuggling 35 tons of cocaine from the Apiay base to El Paso, Texas. Two have been released, while the others are in the US awaiting trial in military courts.

In line with its resistance to the International Criminal Court in The Hague, the US says immunity from local prosecution is key in places like Colombia because politically motivated claims could be made against its troops, who are put into dangerous combat zones that other countries often shun.

US Ambassador William Wood insists that the wayward US troops will be punished harshly, if found guilty, in US military courts. "Immunity does not mean impunity," Wood said last month.

A handful of Colombian legislators have invited Mr. Wood to testify before Congress, though they can't compel him to appear. The lawmakers decry what they see as a double standard. While a record 200 Colombians have been extradited to the US under Mr. Uribe, Americans who commit crimes here are believed to get preferential treatment.

"The minimum that we want is for them to inform us about how the investigations are going in the United States," says Sen. Jimmy Chamorro. "Obviously, we believe that the treaty should be revised, but the political reality is that it's not going to be revised. That would be disastrous for [Uribe's] democratic security strategy."

Indeed, Colombia, and specifically Uribe, with his hard-charging military offensive against leftist guerrillas who have been waging war for 40 years, are heavily dependent on US military aid. As part of the five-year, $3 billion antidrug and antiterror package known as Plan Colombia, the US government is allowed to send up to 800 military and 600 civilian contractors to Colombia at any one time. According to US officials, 7,000 troops have served in Colombia in the past 2-1/2 years.

But it's looking unlikely that the 1974 treaty that extends diplomatic treatment to US soldiers in Colombia will be revised.

"We believe that the bilateral agreement has served the US and Colombia well for the last 30 years," said a US Embassy spokesman. Nonetheless, the topic was discussed at a meeting of US and Colombian senior officials in Cartagena in April.

Last month, US Southern Command chief Gen. Bantz Craddock insisted during a trip here that the soldiers would be adequately punished. "The required persons will be held accountable," he said.

During General Craddock's visit, El Tiempo, a Colombian newspaper, reported that US and Colombian officials talked about replacing the immunity treaty with a Status of Force Agreement (SOFA) that would allow some crimes by US soldiers to be prosecuted in Colombia.

But when recently asked whether there would be a change to the treaty, Wood responded: "No."

Negotiating such a treaty is time-consuming and politically tricky in a year when Uribe is trying to win reelection based on the success of his security strategy, which relies heavily on US help.

The latest incidents regarding US soldiers here have caused Colombians to rehash older incidents in which they believe Americans got off lightly. In a 1999 case, Col. James Hiett, a former military attaché at the US Embassy here, received a five-month prison sentence for laundering money after his wife, with the help of their Colombian chauffeur, used the Embassy mail service to traffic cocaine. Hiett's wife, Laurie, received five years in prison, while the driver was sentenced to eight years in a Colombian jail and is wanted for extradition by US authorities.