WASHINGTON - US President Barack Obama tried to strike a middle ground on Friday on questions about broad surveillance practices conducted by the US National Security Agency, saying some checks are needed on the system but "we can't unilaterally disarm."At a White House news conference, Obama said he would spend the next few weeks sorting through the recommendations of a presidential advisory panel on how to rein in the NSA in the wake of disclosures from former US spy contractor Edward Snowden. Obama said it is possible that some bulk phone data collected by intelligence agencies could be kept by private companies instead of the US government as a way of restoring Americans' trust in the program."We can't unilaterally disarm," said Obama. But he said data collection could be "refined" to give the public more confidence that privacy is not being violated.Questions about US government spying on civilians and foreign officials burst into the open in June when Snowden, now in Russia, leaked documents documenting widespread collection of phone and email. Snowden has been charged with divulging classified information and the United States has unsuccessfully sought his return to stand trial.Obama conceded that the revelations have led to "an important conversation that we needed to have" about balancing security needs and privacy, but he said Snowden's actions have hurt US interests."As important and as necessary as this debate has been, it is also important to keep in mind that this has done unnecessary damage to US intelligence capabilities and US diplomacy," he said.The president said the leaked information had given some countries who have worse records on human rights, privacy protection and freedom of dissent than the United States the leeway to disparage US policies."That's a pretty distorted view of what's going on out there," he said.He declined to answer whether he would consider granting Snowden immunity from prosecution, saying he could not comment on a legal proceeding.One of the recommendations of a blue-ribbon panel appointed by the president to propose reforms to US surveillance was to halt the bulk collection of phone call records, known as "metadata."Asked whether he would adopt that proposal, Obama suggested there was justification for that collection, but said that the process could be done differently.Having all of that data in one place would make it possible to track the calls of a known terrorist into the United States, giving the NSA confidence it could follow up on possible threats, he said."The question we're going to have to ask is, can we accomplish the same goals that this program is intended to accomplish in ways that give the public more confidence that, in fact, the NSA is doing what it's supposed to be doing," he said.Obama said he is confident the security agency is not engaged in domestic spying.