The oldest living CIA agent believes Russia sank its hooks into the Republican Party well before President Donald Trump emerged as a viable candidate.

Peter Sichel was one of the CIA's first agents at the start of the Cold War, and he sees evidence of Russia's spycraft against Trump and the GOP in the Senate Intelligence Committee, reported The Daily Beast.

"One great advantage the Soviets always had over us, is that they played the long game. We thought in terms of quarters, whereas they thought in terms of years or even decades," Sichel said. "They were opportunistic, willing to let matters gradually develop until the right political faction or right leader to support had emerged."

Senate investigators found the Kremlin sought to infiltrate the Republican Party long before Trump became its nominee as part of Russian president Vladimir Putin's effort to deny the White House to Hillary Clinton.

Putin had fostered right-wing political movements across Europe to gain influence there, and Trump's presidential campaign promoted many of the same nationalist themes, and Sichel found numerous instances where Trump campaign operatives opened themselves up to possible Russian blackmail.

"The KGB were absolute masters at it," Sichel said, "and they would use whatever they could get their hands on. A favorite was honey traps [or sexual entrapments], but bribes, favors, whatever they could find. And once they had their hooks into you, they owned you."

Paul Manafort stayed in close contact with Russian spy Konstantin Kilimnik throughout the campaign, while Donald Trump Jr., Jared Kushner and Michael Flynn met with Russian intelligence operatives promising dirt against Clinton.

"The key thing is that all of them then lied about it to investigators, and that's where the potential blackmail comes in. Imagine if the FBI hadn't caught Flynn out, and he had remained in his post," Sichel said. "The Russians knew he lied — I'm sure they taped all their communications with him — so they would have had him over a barrel forever."

The 97-year-old Sichel said the president himself continued to compromise himself by lying about his own dealings with Russia.

"I know he doesn't see it this way, but by having all this stuff brought out in public, it removes the blackmail threat," Sichel said. "The smartest thing Trump could have done when all this started to break was to just come out and say, 'Yes, it appears there was Russian involvement with my campaign, but that's over with now, I'm the president, so let's move on.' But he didn't do that, obviously. Perhaps there were reasons why he couldn't."