Trump threatens North Korea at joint Turnbull press conference

US President Donald Trump has warned a White House press conference with Australian Prime Minister Malcolm Turnbull the world might be in for a "very unfortunate day" if America's latest sanctions on North Korea do not curb the rogue regime's nuclear missile program.

President Donald Trump and Australian Prime Minister Malcolm Turnbull shake hands during a joint news conference Source: AP

While the leaders agreed on continuing pressure on North Korea with sanctions, "merit based" immigration and dealings with China and Syria, they did differ on the Trans-Pacific Partnership and gun control.

"We'll have to see," said Mr Trump, when asked if all options are still on the table if the sanctions don't work.

He did not rule out a "very rough day" with a military response toward North Korea.

"Maybe very unfortunate for the world," the president said.