Sen. Lindsey O. Graham (R-S.C.). (Andrew Harnik/AP)

Sen. Lindsey O. Graham (R-S.C.) called on President Trump to lay out his strategy toward Iran as the country faces its largest protests since 2009, saying such a move would help bolster the United States in its conflict with North Korea.

Predicting that the new year will be one of “opportunity and extreme danger,” Graham said Trump should withdraw from the Iran nuclear agreement in 2018 and give a national address explaining his approach.

Graham warned that North Korea is watching how the United States conducts itself as protests in Iran continue for a third day, and he said that Trump’s tweeting of support for the Iranian people is not an adequate response.

“The Iranians are watching us in North Korea, and North Korea is watching us in Iran,” Graham said in an interview with CBS’s “Face the Nation.” “We’ve got a chance here to deliver some fatal blows to really bad actors in 2018, but if we blink, God help us all.”

Graham spoke after two Iranian demonstrators were confirmed killed in the protests, which began Thursday in response to economic problems in the country. The demonstrations have since broadened into condemnation of the political and cultural repression in Iran.

Trump has tweeted several times in support of the demonstrators, writing Sunday that the United States is “watching very closely for human rights violations.”

But Graham, who called the protests evidence of former president Barack Obama’s foreign policy failures, said it’s “not enough to watch” and post on Twitter.

“President Trump is tweeting very sympathetically to the Iranian people, but you just can’t tweet here. You have to lay out a plan. If I were President Trump, I’d lay out a plan as to how I would engage the regime.”

On domestic policy, Graham said Congress should reach a deal on immigration, a border wall and the status of “dreamers” — undocumented immigrants who came to the United States as children — in January. He predicted that Republicans and Democrats will not “come together” on health care in 2018.