KANDAHAR (Reuters) - It is unclear if the United States will be able to pay troops on time in the event of a debt default, the top US military officer told troops in Afghanistan on Saturday. Admiral Mike Mullen, chairman of the US militarys Joint Chiefs of Staff, said Pentagon officials were working hard to plan for a potential default but cautioned that the circumstances were extraordinary. So I honestly cant answer that question, he told troops at Kandahar air base in southern Afghanistan, as several expressed anxiety over budget wrangling in Washington. Potentially suspending pay to US forces waging wars in Afghanistan and Iraq is an extremely sensitive subject in the US and Mullen acknowledged that many troops lived paycheck to paycheck. So if paychecks were to stop, it would have a devastating impact, Mullen said, answering questions from troops. Id like to give you a better answer than that right now, I just honestly dont know, he said. The United States has warned that it will run out of money to pay all of its bills after Aug 2 without a deal from Congress to raise a $14.3 trillion debt ceiling. Where US troops fall in priority for payment in a default has not been made clear. Mullen said he believed that troops would be paid eventually, regardless of what happens. I have confidence that at some point in time whatever compensation you were owed you will be given, he said. But I dont know mechanically exactly how that would happen. And it is a huge concern. He played down the possibility that a default would undercut military operations or force the US defence department into a partial shutdown, saying were going to continue to come to work. I dont expect it will affect - certainly in the short term - operations here or operations around the world, Mullen later told another gathering of troops at Camp Leatherneck, in Helmand province. While a group of congressmen pushed forward a bill this week to ensure that the active military servicemen still get paid in the case of default, theres no firm plan yet. The White House hasnt made any assurances and neither has the Treasury Department. The top US military officer made an unannounced trip to Afghanistan on Friday, aiming to reassure a country rattled by a wave of high-profile attacks and assassinations. Admiral Mullen said US officials had long predicted the kind of attacks that have shaken southern Afghanistan and Kandahar province in recent weeks. Were not surprised at the spectacular attacks. We thought thats where theyd try to go. Thats where theyre going and weve got to work hard to prevent that, Mullen told reporters before departing for Kandahar province. A suicide bomber killed the mayor of Kandahar on Wednesday, compounding fears of a dangerous power vacuum in Afghanistans south in the wake of the assassination of President Hamid Karzais half-brother, Ahmad Wali Karzai.