US Secretary of State Rex Tillerson pauses in his remarks welcoming Organization of American States (OAS) Secretary General Luis Almagro (not pictured), prior to a bilateral meeting, at the State Department, in Washington, October 13, 2017. [Photo/Agencies]

"The president has also made clear to me that he wants this solved diplomatically," Tillerson said in an interview with CNN.

"He (Trump) is not seeking to go to war," Tillerson said, adding that "those diplomatic efforts will continue until the first bomb drops."

Despite Tillerson's stress on diplomacy, White House National Security Adviser H.R. McMaster said in a separate interview with Fox News on Sunday that Trump would do whatever is necessary to prevent an attack from the Democratic People's Republic of Korea (DPRK) on the United States.

"He's (Trump) going to do anything necessary to prevent that from happening," said McMaster. "If he (the DPRK leader) thinks the development of this nuclear capability is keeping him safer, it's actually the opposite."