NEW YORK — A wealthy arms dealer with a checkered past sought to make millions of dollars by selling heavy weaponry to Colombian militants who’ve been branded terrorists by American authorities, a prosecutor said Wednesday at the start of the dealer’s trial.

When approached by men posing as members of the Revolutionary Armed Forces of Colombia — classified by the United States as a terrorist group — Monzer al-Kassar “without hesitation agreed to supply them with everything they asked for and more,” Assistant U.S. Attorney Brendan McGuire said in opening statements in Manhattan federal court.

Told they needed surface-to-air missile systems, rocket-propelled grenade launchers, thousands of machine guns and millions of rounds of ammunition for the Colombian rebels, al-Kassar responded, “No problem,” the prosecutor said.

The Syrian-born al-Kassar and a co-defendant, Luis Felipe Moreno Godoy, face multiple charges including conspiracy to provide aid and equipment to a terrorist organization and to kill U.S. citizens and officials.

Al-Kassar’s lawyer insisted his client was a legitimate businessman who believed the deal was legal.

“There’s nothing illegal about being an international arms merchant,” said the attorney, Ike Sorkin.

Cooperators with the Drug Enforcement Administration first contacted Al-Kassar in late 2006, telling him they represented the Colombian rebel group, known as FARC. They arranged to meet with al-Kassar and Godoy, his assistant, in 2007 at al-Kassar’s palatial home in Marbella, Spain, near the southern resort city of Malaga.

The evidence against the men includes secretly recorded videotapes of the sitdowns that “will take you into the heart of the weapons deal designed to kill Americans,” McGuire told jurors.

During the sting, more than $400,000 was wired from New York to Spain as down payment, but no weapons ever changed hands.

An indictment unsealed last year said al-Kassar has provided military equipment to violent factions in Nicaragua, Brazil, Cyprus, Bosnia, Croatia, Somalia, Iran and Iraq.

“Some of these factions have included known terrorist organizations, such as the Palestinian Liberation Front,” the indictment said, “the goals of which included attacks on United States interests and United States nationals.”

Besides “bombings, massacres, kidnappings and other acts of violence within Colombia,” FARC is “the world’s largest supplier of cocaine,” the indictment said.