Sen. James Lankford James Paul LankfordMcConnell works to lock down GOP votes for coronavirus bill Charities scramble to plug revenue holes during pandemic Warren calls for Postal Service board members to fire DeJoy or resign MORE (R-Okla.) is calling on President Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE to "apply pain" to punish Russia for its efforts to meddle in the 2016 presidential election.

Lankford, who sits on the Senate Intelligence Committee investigating Moscow's role in the election, told ABC News's "Powerhouse Politics" podcast that he was pleased to hear the president acknowledge on Thursday that Russia had interfered in the election.

But Washington, he said, must "continue to apply pressure" to deter future meddling attempts by the Kremlin.

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"I'm so glad to hear him step out and to be able to say that, but it's also important that we continue to apply pressure," Lankford said. "Once you know they're trying to interfere in our election system, what do you do? How do you apply pain?"

"So my issue now is: What is the clear pain that Russia will experience based on their actions?" he added. "Because I don't think they change the behavior until they actually have experienced some sort of pain."

Lankford proposed a two-tiered response to the meddling efforts, consisting of continued sanctions against Russia and the development of a "cyber doctrine" — a formal plan for responding to cyberattacks.

“It's something we worked with the Obama administration for years on,” he said. “To have a clear policy that can be put out, that if any nation, whether it's North Korea, Iran, China, Russia, whoever it may be — if they try to interfere in any of our infrastructure, or our systems through a cyberattack, we have a structured response that they know: ‘If you do this, then this is how we respond.’ "

Lankford's comments came as Trump prepares to meet with Russian President Vladimir Putin Vladimir Vladimirovich PutinFBI chief says Russia is trying to interfere in election to undermine Biden Traces of nerve agent found in water bottle in Navalny's hotel room, colleagues say Russia: US trying to foment revolution in Belarus MORE on Friday during the annual Group of 20 summit in Hamburg, Germany.

It isn't yet clear if Trump will bring up Russia's interference in the election with Putin during the highly anticipated meeting.