The Trump administration’s back-to-back controversies over its Russian ties have at least one thing in common: Ambassador Sergey Kislyak.

A Washington fixture with a sprawling network, Moscow’s top diplomat in the U.S. has emerged as the central figure in the investigations into Trump advisers’ connections with Russia.

In a matter of weeks, contact with Kislyak led to the firing of a top adviser to the president and, on Thursday, prompted calls for the attorney general to resign.

Observers note Kislyak is a somewhat unlikely figure to cause controversy.

Over the course of a long diplomatic career, he’s led the life of a somewhat typical global envoy – making himself a reliable presence on the circuit of receptions, teas and forums that make up the calendar of any ambassador.

He is quiet, careful, rumpled and portly. He is a fierce defender of Russia’s prestige who rarely gives interviews and even more rarely makes news on his own. He is not considered especially close to Russian President Vladimir Putin.

Kislyak, 66, was trained as an engineer before attending the Soviet Union’s Academy of Foreign Trade and joining the Foreign Ministry in 1977, at the height of the Cold War.

John McLaughlin, who was acting director of the CIA during the Clinton administration, told CNN that it is unlikely Kislyak is connected to Russia’s espionage agency.

“I don’t think he’s a spy literally. He is a veteran diplomat,” McLaughlin said.

But “he’s very clever, he’s very experienced,” McLaughlin said Thursday on MSNBC-TV. “He would certainly be collecting information. That’s what diplomats and spies do.”

– From news service reports