Tillerson US Columbia

Secretary of State Rex Tillerson, right, shakes hands with Colombian Foreign Affairs Minister Maria Angela Holguin, left, at the State Department in Washington, Monday, Nov. 20, 2017. (AP Photo/Susan Walsh)

An end to the world’s longest running civil conflict has saved potentially thousands of lives so far this year in Colombia and brought desperately needed stability to a region long plagued by drug trafficking and violent crime.

Violence between the Colombian military and the Revolutionary Armed Forces of Colombia (FARC) guerrilla group killed nearly 3,000 soldiers, rebels and civilians at the peak of fighting in 2002. So far, the total is zero this year, according to the Colombian Center for Resources on Conflict Analysis (CERAC).

That remarkable drop is due to a groundbreaking peace accord implemented late last year, and reflects years of leadership and cooperation between the United States and Colombia.

President Donald Trump would be wise to maintain that close relationship moving forward, particularly as neighboring Venezuela descends further into chaos and dictatorship.

Earlier this year, Mr. Trump threatened to decertify Colombia as a partner in the international war on drugs if Colombian President Juan Manuel Santos did not ramp up efforts to eradicate illicit coca cultivation.

Mr. Santos ended aerial herbicide spraying in 2015 out of fears that the chemicals involved could harm rural villagers and damage legal crops. Since then, coca production is up to troubling highs, but the United States should work with Colombia to combat illegal drug production rather than turning its back.

Earlier this month, Vice President Mike Pence met with Colombian leaders to tone down Mr. Trump’s rhetoric and offer more time for Colombia to get a handle on the problem. That is a more sensible approach.

Secretary of State Rex Tillerson also met with Colombia’s Foreign Minister, Maria Angela Holguin, last week to discuss peace-building in the region.

“Colombia is the strongest ally for the United States in Latin America,” said Ms. Holguin following the meeting.

The United States should maintain its partnership with Colombia; indeed, that the country is more stable and peaceful than it has been in decades should serve to strengthen the alliance.

There is a significant risk that other illegal armed groups will step into the vacuum left by the disbanding of the FARC. Other criminal organizations already appear to be gaining strength, and the rise in coca production suggests that funding for criminal networks is readily available.

Stability in Colombia is a critical bulwark against an increasingly radical Venezuela, where President Nicolas Maduro has assumed broad powers and all but dissolved its democratically elected Legislature.

Mr. Trump has taken a rightfully strong stance against those attacks on Venezuelan democracy. He must remain firm in opposing efforts to rewrite the country’s constitution and consolidate power for Mr. Maduro and his socialist party.

In that fight, the United States has no stronger ally than Colombia.

Peace with the FARC is to be celebrated. But Colombia needs the United States as much as ever moving forward, and the United States needs a strong partner in the region. Mr. Trump should work to preserve that partnership.