At least 3.5 million young people and retired soldiers have joined the North Korean military to fight in the event of a war against the U.S., state media said, adding that people are rising up "to retaliate against" Washington.
"At the end of the day if the North Koreans evolve into a fully replete nuclear weapons state with ICBMs (intercontinental ballistic missiles) with miniaturised warheads on top then, well, the Chinese view is, the U.S. will then just have to accept that reality", Mr Rudd said.
The restrictions came after North Korea's latest missile tests, which it claimed involved the launch of intercontinental ballistic missiles.
He said this: "North Korea had best not make any more threats to the United States".
"These statements are irresponsible and unsafe, and also senselessly provide a boon to domestic North Korean propaganda which has long sought to portray the United States as a threat to their people", read the letter which was spearheaded by Rep. John Conyers of Missouri. On Thursday, Trump said his original statement "wasn't tough enough".
They further warned that Trump would be held responsible by Congress and the American people if a "careless and ill-advised miscalculation results in conflict that endangers our service members and regional allies".
Now is the time for statesmanship and cool-headed diplomacy on all sides. -North Korean relations and Americans imprisoned in North Korea, the source said.
"They discussed the need to confront the increasingly unsafe situation associated with North Korea's destabilizing and escalatory behavior،" the White House said in a statement.
Trump and Secretary of Defense James Mattis have both used strong language pertaining to North Korea's threats.
"Concerned parties must exercise restraint and avoid remarks and actions that escalate tensions on the Korean peninsula", it cited the Chinese president as saying.
White House officials have insisted the investigation is not created to apply additional pressure on China as it relates to North Korea despite the president's previous remarks that he would be more amenable on trade if China stopped Pyongyang's nuclear program.