"What I have said is that if we had actionable intelligence against high-level al-Qaeda targets and the Pakistani Government was unwilling to go after those targets, then we should. Now my hope is that does not come to that, that, in fact, the Pakistani Government will recognise that we have Osama bin Laden in our sights, then we should fire, that we should capture," he told CBS in an interview.
Obama who visited neighbouring Afghanistan Sunday, however, told the channel that Washington's strategy should be that if Pakistan does not take action in the event of having actionable intelligence against high-value terror suspects, the United States should.
Conditions in Afghanistan are "precarious and urgent," Democratic presidential candidate Barack Obama warned in an interview aired Sunday as he renewed his call for an immediate increase in US troops there.
"The Afghan government needs to do more, but we have to understand that the situation is precarious and urgent here in Afghanistan," Obama said.
Obama called for at least two more brigades to be sent to Afghanistan. "Now is the time for us to do it. I think it's important for us to begin planning for those brigades now," he said.
Obama said Washington needed to take a regional approach to the problem, particularly by engaging Islamabad regarding what he described as a "growing" number of extremist training camps in Pakistan near the Afghan border.
"I think that what we'd like to see is the Pakistani government take out those training camps," he said. In Kabul, Obama met with Afghan President Hamid Karzai, who has been criticised by the Illinois senator for not doing enough to rebuild his war-torn country.
The meeting, which lasted nearly two hours and included lunch at the Presidential Palace in Kabul, covered a range of issues including terrorism and Afghanistan's vast narcotics trade, Karzai's spokesman said.
"The discussions were focused on the significant progress that we've made but also on the unmet challenges that we still have ahead of us," Homayun Hamidzada told reporters as Obama and his party headed to the airport.
"The discussions also focused on the difficulties we're facing, the difficult challenges in the fight against corruption, counter-narcotics and also the continuing threat of terrorism and fundamentalism," he said.
Obama has made Afghanistan a key part of his foreign policy pledges, saying it - not Iraq - should be the focus of the so-called "war on terror" and promising to send more troops to battle insurgents here if elected.
He has been critical of Karzai's administration, telling CNN this month it had "not gotten out of the bunker and helped to organise Afghanistan and (the) government, the judiciary, police forces, in ways that would give people confidence."
Asked if Obama's comments on Karzai came up at the meeting, Hamidzada said the talks were friendly and discussions were at a "broad level".
"While we're making significant progress in rebuilding our country ... we're spending lots of our resources and energy fighting terrorism that is exported from the south," he said, in a clear reference to Pakistan, where US officials have said extremists have sanctuary.
Obama and the other senators meanwhile reaffirmed bipartisan US support for Afghanistan, Karzai's office said.
Before the meeting, Obama - on his first trip to Afghanistan - and two US senators accompanying him started the day with breakfast with US troops at a US military camp in Kabul.
In a radio address Saturday to coincide with Obama's visit, his Republican rival John McCain criticised the senator for announcing his strategy for Afghanistan and Iraq before his fact-finding tour.