US President Donald Trump has promised to introduce additional national security steps, a day after a court refused to reinstate his travel ban on refugees and citizens from seven Muslim-majority countries.
Mr Trump has also expressed confidence his order would ultimately be upheld by the courts.
The White House is not ruling out the possibility of rewriting Trump's 27 January executive order in light of the actions by a federal judge in Seattle and an appeals court in San Francisco that put the directive on hold, an administration official said.
The order, which Mr Trump has called a national security measure to head off attacks by Islamist militants, barred people from Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen from entering for 90 days and all refugees for 120 days, except refugees from Syria, who are banned indefinitely.
"We are going to do whatever's necessary to keep our country safe," Trump said during a White House news conference with visiting Japanese Prime Minister Shinzo Abe.
He did not answer directly when he was asked whether he would sign a new travel ban.
"We'll be doing something very rapidly having to do with additional security for our country. You'll be seeing that sometime next week," Mr Trump said, without providing specifics.
His administration would also continue to go through the court process, he said.
"And ultimately I have no doubt that we'll win that particular case," he added, referring to the ruling by a three-judge panel of the 9th US Circuit Court of Appeals in San Francisco, which upheld the lower court's suspension of his ban.
The administration could appeal the ruling to the US Supreme Court as early as today (NZT).
NBC News reported that White House lawyers were working on a rewrite of Trump's executive order that could win federal court approval.
"The administration is looking through all the options on how to move forward. But we'd like to win the case in court," the administration official told Reuters.
Mr Trump, who has repeatedly expressed frustration with the week-old court-mandated suspension, tweeted that the appeals court decision was "disgraceful."
"SEE YOU IN COURT," he said in a Twitter post on Thursday after the ruling.
The Supreme Court is currently one short of its nine-member strength and ideologically split, with four liberal justices and four conservatives, pending Senate confirmation of Trump's conservative nominee, Neil Gorsuch, to the bench.
The administration would need five of the eight justices to vote in favor of reinstating the travel ban while litigation continued in the lawsuit brought by Washington and Minnesota. That would mean the administration would need to win over at least one of the liberal justices.
The administration has been defending Trump's ban in more than a dozen additional lawsuits now moving through the court system.
Justice Department lawyers argued in a federal court in Virginia overnight against a preliminary injunction, which would put a longer hold on the executive order than the Seattle court ruling.