The capture of Joaquin Perez Becerra, alias Alberto Martinez, was the latest sign of improved cooperation between two nations since Santos took office in August. Under Santos' predecessor, Alvaro Uribe, the neighbors were at loggerheads and briefly on the verge of war in 2008.

Chavez "didn't hesitate. He ordered him arrested, and he will give him to us," Santos was quoted as saying in an interview published Monday in El Tiempo newspaper: "It's another sign that Chavez is keeping his word."

According to a statement issued Monday by Colombia's national police, Perez headed a network of European supporters for the Revolutionary Armed Forces of Colombia, or FARC, from his base in Sweden. He is a 30-year FARC veteran who ran the rebels' website and arranged arms purchases, police said.

"It's clear that cooperation between the two governments is functioning and that Santos' strategy of diplomacy is working better than the strategy of confrontation we had in the past," said Alejo Vargas, a political science professor at the National University of Colombia in Bogota.

Relations between the two countries soured in 2007 when Uribe's conservative government abruptly canceled Chavez's mediation efforts to win the release of FARC hostages and accused him of harboring rebel leaders on Venezuelan territory. Chavez fired back, saying Uribe had links to right-wing paramilitary militias.

After Colombian forces briefly invaded Ecuador in March 2008 to kill FARC leader Raul Reyes, the leftist Venezuelan leader sent tanks to his country's border with Colombia and mobilized troops. Chavez also froze cross-border trade, which cost Colombian companies as much as $4 billion a year in sales of food, apparel and other exports to Venezuela.

In three meetings since Santos took office, the leaders have publicly vowed to patch up their differences. Chavez has reopened his borders to Colombian trade and promised to pay $800 million owed to Colombian firms.

Chavez strenuously denies past charges by Colombian and U.S. officials that several top FARC leaders are camped in Venezuelan territory with his implicit approval. In December, Chavez extradited Nilson Teran, the leader of a smaller National Liberation Army rebel group, to Colombia at the request of the Santos government.

Santos has faced criticism in the United States for his promise to extradite Walid Makled, a suspected drug trafficker arrested in the Colombian border city of Cucuta, to Venezuela. U.S. officials have also sought to extradite the Venezuelan suspect; they reportedly believe Makled could implicate officials close to Chavez in illegal trafficking.

"Santos is acting strictly according to the law, which says the first extradition request is what counts and that was Venezuela's," said Vargas, the political science professor. "The problem is that under Uribe, we became accustomed to believing that whatever desire the U.S. had was what became the order of the day."

El Tiempo reported that Colombian intelligence officials intercepted a message from FARC leader Ivan Marquez summoning Perez to an emergency meeting. With "international cooperation," officials ascertained that he was arriving Saturday in Caracas, the Venezuelan capital, on a Lufthansa flight from Germany, information that Santos passed along to Chavez.

**Kraul is a special correspondent.