North Korea should not underestimate US President Donald Trump's resolve to stop the communist regime from developing a nuclear missile capable of striking the US, a ranking Republican senator said Tuesday after dinner with Trump the previous day.

"If I were North Korea, I would not underestimate President Trump's resolve to stop them from getting a missile to hit our homeland," Sen. Lindsey Graham (R-SC) told reporters, a day after he and Sen. John McCain (R-AZ) had dinner with Trump at the White House, according to AP.

Graham also posted a Twitter message saying, "Pres @realDonaldTrump is NOT going to let the nutjob in North Korea develop a missile -- with a nuclear weapon on top -- that can hit the US."

In an interview with Fox News, Graham also said that Trump "doesn't want a war any more than I do, but he's not going to let them get a missile. That's where they're headed. And China needs to up their game to stop this before it gets too late."

The senator said he prefers to solve the problem through diplomacy and sees military force as a "last resort."

McCain also told reporters that the Trump administration's hardline rhetoric against the North is "legitimate."

"Obviously you have to follow words with action, but I think their expressed concern is very legitimate. And I don't think it's inflammatory rhetoric," the senator told reporters. McCain also said the North's leader is "intent on having the capability to strike the United States of America. That is the threat."

McCain said Trump is "exploring all options" but military action "would be the last one."

During a Senate Armed Services Committee hearing later in the day, McCain also expressed serious concern about the North.

"A North Korea missile with a nuclear payload capable of striking an American city is not longer a distant hypothetical but an eminent danger, one that poses a real and rising risk of conflict," he said.

He also criticized China for retaliating against South Korea for hosting the US THAAD missile defense system.

"China is doing all of this to stop the deployment of a missile defense system which is only necessary because China has aided and abetted North Korea for decades," he said.

Calls have been growing in the US for curbing the North's ICBM capabilities even through the use of military force, despite repeated warnings from experts that such a strike could quickly escalate into a second Korean War as the North is sure to strike back.

Last week, Graham said that the US should launch a preemptive strike on North Korea if that's what it takes to stop Pyongyang from building a missile capable of hitting the country, arguing that war with the North won't reach the US, but a North Korean ICBM could.

Also Tuesday, Sen. Cory Gardner (R-CO) said the US should use every possible means to deter the North, including military measures if necessary.

"The US will deploy every and all economic, diplomatic and if necessary, military tool at our disposal to deter Pyongyang and to protect our allies," he said during a think tank discussion.

Gardner also urged China to do more to pressure the North.

"The road to stopping Pyongyang undoubtedly lies through Beijing. China is the only country that holds both the diplomatic and economic leverage necessary to put the pressure, maximum pressure on the North Korean regime," Gardner said during a think tank discussion.

"Beijing's reluctance to do so, however, is the reason the regime acts so boldly and with relatively few consequences. China must now move beyond mere articulation of concern and lay out a transparent path of focused pressure to denuclearize North Korea," he said.

The senator also urged Trump to condemn China's economic retaliation against South Korea over THAAD.

"President Trump should unequivocally condemn the economic pressure by Beijing with Seoul over the deployment of Terminal High Altitude Area Defense or THAAD on South Korean territory. THAAD is a defensive system and in no way threatens China and Beijing knows this," he said. (Yonhap)