Mexican President Felipe Calderon is struggling to keep his war against organized crime on track after losing some of his top crime-fighting officials in a plane crash last week.  The cause of that plane crash is still under investigation, but more than 4,000 people have died so far this year in violence connected to criminal gangs.  As VOA's Greg Flakus reports from Houston, the United States could be drawn into the conflict south of the border.

The roster of violent crime in Mexico in recent weeks is alarming:  headless bodies found hanging from bridges, policemen ambushed by assailants with automatic weapons, grenades dropped into a crowd of people in a public square, killing and injuring several.

Last week, a plane carrying Interior Minister Juan Camilo Maurino and other top officials crashed in a Mexico City neighborhood.  Many Mexicans suspect drug traffickers caused the crash, although authorities say there is no evidence of foul play.

President Calderon says the incident that robbed him of his chief aide in the war against organized crime will be investigated thoroughly.

He says international experts are examining the wreckage to determine what caused the crash and that he, as president and friend of the victims, has a special interest in knowing the cause.

Calderon has been fighting a difficult and costly battle against drug gangs, kidnappers and other organized criminals since he took office in December, 2006.  The fight has been complicated by corruption within his own police forces and by some police quitting their jobs after being targeted by drug gangs.  The Mexican leader has relied on the army to carry on much of the fight.

Former Mexican Foreign Minister Jorge Castaneda, speaking here in Houston in September, gave a frank and frightening assessment of the situation in his country.

"Very clearly, we have an enormous challenge in Mexico, regarding drugs, regarding criminality and regarding law enforcement in general," Castaneda said.  "And this, by the way, is not just an issue for the United States because of the border and because, obviously, part of the Mexican drug problem has to do with U.S. demand for drugs either produced in Mexico or passing through Mexico."

Castaneda said Mexicans have been the victims of most drug gangs and kidnappers.  But he said Americans could also face danger when they are in Mexico, noting that around one million U.S. citizens live in Mexico and another 22 million visit the country each year.

"The risk is, either that it spills over, or that the violence begins affecting Americans in Mexico," said Castaneda.

This is also the concern of security analyst Fred Burton at the Austin, Texas-based Stratfor firm, a private intelligence and analysis company.

"If you talk to the border sheriffs, which I do - if you talk to the police departments along the border, they will tell you they have a significant problem with cross-border abductions, murders, the homicide rate, and it impacts on us all in the United States," said Burton.

Although Mexico has now developed a drug consumption problem of its own, most of the drugs produced there are sold in the United States, the world's largest market for narcotics.   Burton says the money from drugs helps criminal gangs bribe their way into almost every level of government.

"You are looking at an industry that is perhaps as large as $100 billion of cash flowing into Mexican coffers," Burton continued.  "Calderon has a difficult job and, if you look at it from his perspective, I don't know how you combat this problem without US assistance."

But direct US involvement in Mexico is difficult given Mexican sensitivities about their country's sovereignty.  Jorge Castaneda thinks more direct US involvement is necessary, but he says it is not easy to sell to the Mexican populace.

"Clearly the level of U.S. cooperation is insufficient for Mexico to win this war.  Can there be more U.S. cooperation that is politically viable in Mexico and effective in the war? That does not seem to be the case right now. That leaves both presidents, the new American one and Calderon, in a very difficult situation," said Castaneda.

When President-elect Barack Obama takes office in January, he will face a severe financial crisis and wars in Iraq and Afghanistan, problems that present sufficient challenges for any new leader.  But, in addition, he may be facing a worsening situation in a country right next door.