President Donald Trump said Friday "we'll have to see" what the United States will do if sanctions on North Korea fail to deter its nuclear and missile programs.

However, he cryptically warned of a potential "phase two," which may prove "very, very unfortunate for the world." He did not give more details on what action he would take or when he would consider the sanctions failed.

"If the sanctions don't work, we'll have to go phase two. Phase two may be a very rough thing. It may be very, very unfortunate for the world. But hopefully the sanctions will work," Trump said at a joint news conference with Australian Prime Minister Malcolm Turnbull.

Earlier in the day, the Trump administration announced a sweeping sanctions package aimed at curbing the communist dictatorship's weapons development. The measures target one individual, 27 entities and 28 vessels, located or registered in several locations: North Korea, China, Singapore, Taiwan, Hong Kong, the Marshall Islands, Tanzania, Panama and Comoros, the Treasury Department said.

The United States and its allies have tried to choke off financing for Pyongyang's nuclear and missile programs. The strategy includes sanctioning entities that the U.S. believes provide oil and other financial assistance to North Korea.

Last year, North Korea carried out numerous missile launches as well as its sixth and most powerful nuclear test.

The Treasury Department called the sanctions package unveiled Friday the "largest North Korea-related sanctions tranche to date." In a statement, Treasury Secretary Steven Mnuchin said the U.S. is "taking decisive action to block the vessels, shipping companies, and entities across the globe that work on North Korea's behalf."

While Trump's advisors have said they do not want to take military action against the rogue regime, Trump has previously responded to North Korea's provocations with explosive rhetoric. Last year, he said he would bring "fire and fury like the world has never seen" on the country if it threatened the United States.

Speaking with Trump on Friday, Turnbull said Australia is also committed to deterring North Korea's weapons program through its own sanctions and by enforcing United Nations Security Council measures.