Donald Trump has intensified concerns over American intentions towards North Korea by tweeting what appeared to be a veiled threat against the secretive state.
He claimed diplomatic efforts with the Pyongyang regime had failed and said "only one thing will work".
"Presidents and their administrations have been talking to North Korea for 25 years, agreements made and massive amounts of money paid," Mr Trump tweeted.
He accused the regime of violating agreements "before the ink was dry" and was making a fool of US negotiators.
Although Mr Trump did not make clear what his hint meant, the suggestion of military measures was quickly inferred.
Mr Trump and North Korea have been engaged in an escalating war of words in recent months, with the President arguing for decisive military action against the state over its nuclear missile programme.
In his UN General Assembly address last month , the US leader threatened to "totally destroy" North Korea, saying "the United States is ready, willing and able (to act), but hopefully this will not be necessary".
Mr Trump also told a recent gathering of journalists that this period "could be the calm before the storm".
While he did not explain his comments further, a White House spokeswoman said they likely referred to Iran and North Korea.
The outburst follows a series of Twitter rants from the President targeting late night TV hosts and television coverage of US politics.
"Late Night host are dealing with the Democrats for their very "unfunny & repetitive material, always anti-Trump!" he wrote.