As the crisis in Venezuela continues to worsen, the U.S. military reports seeing more militia activity along the country’s eastern border with Colombia. The two main groups operating in the area are Colombia’s National Liberation Army (ELN) and the notorious Revolutionary Armed Forces of Colombia (FARC), both of which self-identify as Marxist. Both groups are currently on the U.S. State Department’s list of foreign terrorist organizations and have been fighting with the Colombian government for more than 50 years, according to one report from NBC.

With the situation in Venezuela becoming more fragile every day, increased illegal activity along the border only complicates matters further. As a result, the U.S. military has begun ramping up intelligence-gathering activities to monitor the groups. According to the head of the U.S. Southern Command (SOUTHCOM), Admiral Craig Faller, the U.S. military is working with the Colombian government to share intelligence and information about what the groups are doing in the no man’s land between the two countries.

“Our principal role working with our Colombian partners is to assist in intelligence sharing,” said Faller while speaking to reporters from Reuters. “What we know, we share.”

According to Faller, both the ELN and the FARC have taken advantage of the crisis to bolster their ranks and gain a stronger foothold in Venezuela. With the closure of the border earlier this year, the rebel groups are now free to control a series of trails many Venezuelan refugees use to escape the country. According to Insight Crime, a watchdog group and think tank, rebel forces are extorting refugees for large sums of cash while battling each other and authorities for control. These trails, also called “trochas” by the locals, have been used for years to move weapons, drugs, and other contraband between the two states.

Further complicating the matter is the lack of response from both the Colombian and Venezuelan governments. Although Colombian President Ivan Duque hopes to modify a 2016 peace deal with the rebels that would effectively implement harsher punishments for rebel fighters, he needs the support of Colombian legislators to do so, according to Reuters. As for the Venezuelan military, many soldiers have long ago abandoned their posts and have fled the country. The ones remaining and still loyal to Nicolas Maduro are needed in populated areas to control unrest. The result is a modern Wild West that could make any attempt at a diplomatic solution in Venezuela much more difficult.

U.S. President Donald Trump has been critical of Maduro since the former took office, and the White House officially recognizes Juan Guiado as Venezuela’s legitimate ruler. So far, the Pentagon has reaffirmed that there are no plans in the works to deploy troops into Venezuela to remove Maduro by force. However, Faller also indicated that SOUTHCOM was prepared to deploy into the region if needed.

“My job is to be ready, be on the balls of my feet, at all times,” he said. “But we’ve been talking to our partners and no one, no one, thinks that a military option is a good idea.”