KAILUA, Hawaii — President Obama praised Congress on Thursday for making it easier to transfer Guantanamo detainees to other countries, but noted that lawmakers’ actions fell short of the flexibility he needs to close the prison.

Obama cited his repeated requests to Congress for cooperation in closing the detention center at the U.S. naval station in Cuba, which he has vowed to do since his first presidential campaign.

"The continued operation of the facility weakens our national security by draining resources, damaging our relationships with key allies and partners, and emboldening violent extremists," the president said in a statement from Hawaii, where he is spending his Christmas vacation, after he signed the National Defense Authorization Act for the 2014 fiscal year.

Provisions in the defense authorization bill, which sets spending and other policies for the Defense Department over the next year, could smooth the way for up to half of the 158 detainees still at Guantanamo Bay to be returned to their home countries.

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When Congress passed the bill, Human Rights First, an advocacy group that has closely monitored conditions at the prison, said lawmakers had laid a "new foundation for bringing the number of Guantanamo detainees down to zero" and closing the prison, which was set up to hold suspected terrorists after the attacks of Sept. 11, 2001.

But in Thursday's statement, Obama faulted Congress for enacting "unwarranted and burdensome restrictions" in recent years that impeded his ability to transfer any of the detainees to U.S. soil so they could be tried and prosecuted in civilian courts.

"For decades, Republican and Democratic administrations have successfully prosecuted hundreds of terrorists in federal court. Those prosecutions are a legitimate, effective and powerful tool in our efforts to protect the nation," Obama said. "Removing that tool from the executive branch does not serve our national security interests."

The new defense authorization bill includes measures that ease what Obama called "rigid restrictions" that have interfered with his ability to negotiate with other countries about where detainees could be sent.

But Obama argued that the relaxation of the rules did not go far enough because it did not "eliminate all of the unwarranted limitations" on prisoner transfers. He asserted that his office must have the flexibility to "act swiftly" when negotiating with other countries about how and where detainees would be transferred.

The president said "in certain circumstances" the rules Congress has put in place could "violate constitutional separation of powers principles" – language that leaves open the possibility that the administration could argue it is not bound by the restrictions it considers unconstitutional.

The president also cited his objections to several sections of the bill that restrict the use of U.S. funds to transfer Guantanamo detainees to U.S. facilities or house them on U.S. soil — arguing that his administration must have that authority.

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Still, Obama called the provisions passed by Congress "an improvement over current law" and "a welcome step" toward closing Guantanamo.

Before setting out for a short hike with his wife and two daughters to Manoa Falls on the Hawaiian island of Oahu, where he is vacationing, the president signed a series of other bills.

Among them was the bipartisan two-year budget agreement that was negotiated this month by House Budget Chairman Paul D. Ryan (R-Wis.) and Senate Budget Committee Chairwoman Patty Murray (D-Wash.).

maeve.reston@latimes.com

Twitter: @MaeveReston