Law enforcement officials in Colombia claim they recently uncovered a possible plot to assassinate President Ivan Duque. According to Reuters, Colombia’s Foreign Minister Carlos Holmes Trujillo went public with the information via a video message on Saturday. In the video, Trujillo described the plot as “credible” and stated three Venezuelan nationals, who are now suspects, had been arrested for possessing “weapons of war.” The weapons are being described as rifles chambered in 5.56.

“Intelligence investigations into possible attacks have been going on for several months,” said Trujillo in the video, according to Reuters. “Added to that is the recent capture of three Venezuelan citizens found in possession of weapons of war, which further increases concerns.”

Tensions between the two neighboring South American nations have been rising ever since Venezuela’s economy began to collapse several years ago. As a result of the worsening conditions in Venezuela, large numbers of the country’s population have been illegally entering surrounding states. The mass influx of people — many of which are starving and have complex medical issues — has created a humanitarian crisis. Earlier this year, the United States deployed one of its two hospital ships — the USNS Comfort — to the region to assist allied nations in caring for the migrants.

“The countries in the region are developing countries, we can’t forget that,” said Simón Bolívar University’s migrant expert Claudia Vargas Ribas during an interview with the BBC. “So receiving this quantity of people has made their internal affairs more complicated.”

Duque, who took power in August, has been critical of the socialist Maduro regime currently ruling over Venezuela. Maduro in return has publicly blamed Colombia for a failed assassination-by-drone attempt earlier this year. Colombian officials deny the accusations, but the relationship between the two states has continued to deteriorate. Before the recent arrest of the three suspects, Colombia protested its neighbor after it was discovered that Venezuelan soldiers have been crossing the border with regularity.

It is estimated that at least three million Venezuelans have left their country since the collapse. According to a report from the BBC, that number is expected to increase by nearly double next year. In addition to Colombia, migrants have also entered Ecuador, Peru, and Brazil among other nations. This year, Nicolás Maduro was elected to another six-year term as ruler of Venezuela. Maduro has long since claimed his country’s woes are solely to blame on the United States and its allies on the continent.