WASHINGTON - With Pakistan keeping the routes for NATO supplies to Afghanistan blocked and raking steps to boost its air defences along the Pak-Afghan border, the United States said it is working hard to keep open channels and get back to work with the Pakistani government. This relationship is complicated. But its also essential to both the United States and Pakistan. We are working very hard to keep open channels and to get back to work together, State Department spokesperson Victoria Nuland told the regular briefing on Friday. The spokesperson was responding to a question about US military officers comments who described the situation, in the aftermath of the deadly NATO strike, as a mess. Nuland said would not comment if her characterisation 'complicated meant 'messy for the current state of relations between the two countries. Im not going to get into parsing words here. She said the US officials have been in constant contact with their counterparts in Pakistan, the latest being the meeting between the US Ambassador to Pakistan Cameron Munter with Foreign Minister Hina Rabbani Khar. We are continuing our intensive engagement including through the recent meeting between Ambassador Munter and Foreign Minister Khar. Obviously we are both trying to roll up our sleeves and get back to work together, Nuland said. With regard to what might emerge from any internal review, I would refer you to the Government of Pakistan on that. We are obviously making very clear that we think we have hard work to do together and we need to get back to it as quickly as we can, she said. Nuland said there is no reason to believe that the Dubai visit of Pakistan President Asif Ali Zardari has anything to do other than his health issue. We wish him a speedy recovery and a speedy return back to his country, she said. We believe that this relationship, while complicated, is essential to both of us. So, were going to continue to work on it, the US official added.