Trump promises to take action on travel

US President Donald Trump promised to take action "very rapidly" to protect the US and its citizens, a day after a federal appeals court firmly kept his travel ban on hold.

He didn't reveal his planned next step to control travel into the US from countries that he considers potential terrorist threats.

"We'll be doing things to continue to make our country safe," Trump pledged at a news conference with Japanese Prime Minister Shinzo Abe.

"It will happen rapidly. We will not allow people into our country who are looking to do harm to our people."

Trump added that still expects to prevail in a legal challenge to his travel ban, despite Thursday's 3-0 ruling by the 9th US Circuit Court of Appeals that kept it from going back into effect.

"Ultimately, I have no doubt that we'll win that particular case," Trump said.

Trump stressed that voters elected him to keep the country secure, "so we'll be doing something very rapidly having to do with additional security for our country. You'll be seeing that sometime next week."

Conjuring images of unspecified danger, Trump said he had "learned tremendous things that you could only learn, frankly, if you were in a certain position, namely president. And there are tremendous threats to our country. We will not allow that to happen, I can tell you that. We will not allow that to happen."

Trump is standing by his argument that national security hangs in the balance despite the loss in court.

White House counselor Kellyanne Conway suggested the next step would be to argue the merits of the executive order.

"The statute provides a president ... with great latitude and authority to protect the citizens and to protect the nation's national security," Conway said.

"This was not argued on the merits. Now that we'll have an opportunity to argue on the merits we look forward to doing that. We look forward to prevailing."

The ruling represented a setback for Trump's administration and the second legal defeat for the new president in the past week.

Trump's decision to sign the executive order late last month has sparked protests at airports around the world as authorities barred scores of travellers from entering the country amid confusion over how to implement the details.

The appellate decision brushed aside arguments by the Justice Department that the president has the constitutional power to restrict entry to the United States and that the courts cannot second-guess his determination that such a step was needed to prevent terrorism.