Trump added that he hopes North Korean leader Kim Jong Un "will find another path".
Earlier this week, Trump reacted to reports that North Korea had produced a compact nuclear warhead and warned the country they "will be met with fire and fury" if they carry out an attack.
His comments came just days after the president's sharpest rebuke, with Trump claiming on Thursday that "fire and fury" might not be "tough enough". Pacific territory of Guam.
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The president gave the US military authority to target al-Shabab in a designated area of Somalia south of Mogadishu with prior notification to the Somali government.
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New signing Romulu Lukaku scored the only goal for Manchester United , the Europa League champions. Goals in Skopje on Tuesday came from Casemiro in the first half and Isco in the second for Real.
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BANK ON THIS: LendingClub surged 10.9% to $6.06 after the peer-to-peer lender's second-quarter earnings beat analysts' forecasts. The S&P hasn't moved more than 0.5 percent in one day since July and has fallen more than 1 percent only twice this year.
The tweet is a signal to Pyongyang that it needs to stand down and start the process of giving up its nuclear arms lest it persists on a path on which Secretary of Defense James Mattis promised would destroy North Korea.
The U.S. and South Korea are due to start joint military exercises from August 21, while Japanese and U.S. military personnel have begun drills on Japan's northern island of Hokkaido that run through August 28.
China's government, via state media, said it would remain neutral if North Korea attacks the US but would defend its neighbor if the USA were to strike first against Kim Jong Un. China, North Korea's only major ally, called on both countries to avoid the "old road" of escalating hostilities.
As North Korean ballistic missiles are liquid fueled, they take some time to prepare for launch, unlike solid fueled ICBMs deployed by the United States and Russian Federation that can be launched on command.
Asked if the United States was ready if North Korea made a hostile act, he said: "We are ready".