Donald Trump took a break from escalating the diplomatic crisis between the US and North Korea on Thursday morning to share an unscientific Twitter poll suggesting he was a "better President" than Barack Obama.

Not yet halfway through his 17-day "working vacation" at a New Jersey golf club, Mr Trump has nonetheless continued to dominate the news agenda by threatening "fire and fury... and power" against Pyongyang over perceived nuclear threats to the US.

North Korea appears to have called the US President's bluff, redoubling its aggressive statements and outlining a detailed plan to target the American Pacific territory of Guam with a series of missile strikes.

But Mr Trump has not let the developing crisis take up all of his time, continuing to attack his fellow Republicans on social media over the failure to pass a reformed healthcare bill.

Shortly after 7am local time, Mr Trump retweeted the conservative-leaning Progress Polls account asking: "Who is a better President of the United States?" Sixty-one per cent voted for Mr Trump, while 39 per cent voted for Mr Obama.