A Republican senator criticized the Trump administration on Sunday for having a 'blind spot' when it comes to protecting the United States from Russia.

South Carolina Sen. Lindsey Graham told NBC's 'Meet the Press' that he doesn't understand why the White House ignored an October 1 deadline for imposing new sanctions on Moscow's defense and intelligence sectors.

'I think that the Trump administration is slow when it comes to Russia. They have a blind spot on Russia I still can't figure out,' Graham said.

'BLIND SPOT': Republican Sen. Lindsey Graham of South Carolina said Sunday that the Trump administration 'is slow when it comes to Russia'

The president has ignored an Oct. 1 deadline – in a law he signed in early August – which required him to impose new sanctions on Moscow

He also strongly suggested that Russian election meddling in 2016 won't be the last of its kind.

In '16, they interfered in our elections. I don't think it affected the outcome, but in '18 and '20, they're coming back against us,' Graham said.

Trump grudgingly signed a sanctions bill into law in August, committing to move the ball forward within 60 days.

The law requires the president to 'issue regulations or other guidance to specify the persons that are part of, or operate for or on behalf of, the defense and intelligence sectors of the Government of the Russian Federation.'

The administration hasn't made any moves in that direction.

Russia's president Vladimir Putin has insisted that his nation wasn't behind election-year meddling in the U.S., but Congress has declared otherwise

Graham said 'Congress will have a way to hold the president accountable. I think he's beginning to understand the threats we face better and better each day.'

He also warned that Russian cyber intrusions pose a dire threat that the U.S. government is only now beginning to contemplate.

'What are the rules of engagement? Did what they do in 2016 – did that amount to an act of war? How do you respond to cyber threats?' asked Graham.

'We're really not well together as a nation in terms of the threats we're facing from the cyber arena. But Russia is going to get worse, if not better.'

'Mr. President, go after Russia because they're coming after us,' he urged.