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

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

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

Mr Trump added that he 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," he said.

Mr 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".

He added that "extreme vetting" is still planned for would-be visitors or immigrants from other countries.

Conjuring images of unspecified danger, Mr 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."

The president is standing by his argument that national security hangs in the balance

The president is standing by his argument that national security hangs in the balance.

He issued an all-caps tweet shortly after Thursday's court ruling: "SEE YOU IN COURT, THE SECURITY OF OUR NATION IS AT STAKE!"

In West Wing comments on Thursday night, he exhibited an air of confidence: "We have a situation where the security of our country is at stake and it's a very, very serious situation, so we look forward ... to seeing them in court.

"We're going to win the case."

The Justice Department said it was "reviewing the decision and considering its options". It could launch an appeal against the restraining order on Mr Trump's travel ban to the U. Supreme Court or it could attempt to remake the case in the district court.

White House counsellor 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," Ms 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 Mr Trump's administration and the second legal defeat for the new president in the past week.

His 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.

US District Judge James Robart in Seattle issued the temporary restraining order halting the ban after Washington state and Minnesota sued, leading to the federal government's appeal.

The Trump administration has said the seven nations - Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen - have raised terrorism concerns. The states have argued that the executive order unconstitutionally blocked entry based on religion and the travel ban harmed individuals, businesses and universities.

The president, in his third week in office, has criticised the judiciary's handling of the case.

Mr Trump has yet to nominate a candidate to be solicitor general, the lawyer who argues before the Supreme Court on behalf of the United States. The president said he will be making that decision over the next week.