President Donald Trump’s eldest son was likely paid at least $50,000 for an appearance late last year before a French think tank whose founder and his wife are allies of the Russian government in efforts to end the war in Syria.

Donald Trump Jr. addressed a dinner on Oct. 11 at the Ritz Hotel in Paris, hosted by the Center of Political and Foreign Affairs. Its president, Fabien Baussart, and his Syrian-born wife, Randa Kassis, have cooperated with Russia in its drive to end the Syrian civil war, according to U.S., European and Arab officials.

In December, Mr. Baussart formally nominated Russian President Vladimir Putin for the Nobel Peace Prize.

Mrs. Kassis is a leader of a political faction endorsed by Russia in negotiations to end the war in Syria. The couple said they don’t represent Russia and are solely focused on ending the Syrian conflict.

The meeting in October represents one in a string of contacts over the past year between members of the president’s inner circle and individuals connected to Moscow and to Russian interests. The Wall Street Journal in November reported Donald Trump Jr.’s appearance at the event.