"If the sanctions don't work, we will have to go to phase two, and phase two may be a very rough thing, may be very, very unfortunate for the world," the president said Friday afternoon.
Trump delivered the remarks to reporters at a joint news conference with Australian Prime Minister Malcolm Turnbull.
"I don't think I'm going to exactly play that card. But we'll have to see. If the sanctions don't work, we'll go to phase two," Trump explained.
Excerpts of Trump's speech about the new sanctions, which is yet to be delivered, state: "I am announcing that we are launching the LARGEST-EVER set of new sanctions on the North Korean regime.
The sanctions target "27 entities and 28 vessels located, registered or flagged in North Korea, China, Singapore, Taiwan, Hong Kong, Marshall Islands, Tanzania, Panama and Comoros," the US Treasury Department said Friday.
Last year, Trump threatened "fire and fury… the likes of which have never been seen before" against North Korea, if the country continues to develop and threaten to use its ballistic missile and nuclear weapons capabilities despite international sanction and condemnation. The president also stated in the fall that "the U.S. has been talking to North Korea, and paying them extortion money, for 25 years. Talking is not the answer!"