For US combat pilots in Afghanistan, there are two reasons to visit Pakistan: to help provide aid to the millions affected by devastating floods, and to improve America's image.
Torrential monsoon rains have lashed Pakistan for two weeks, triggering catastrophic flooding that the UN says has affected 13.8 million people,in a disaster eclipsing the 2004 tsunami that killed 220,000 across Asia.
Entire villages have been washed away. Parts of the country, such as the northwest Swat valley which for years was paralysed by Taliban insurgency, are cut off from the outside world. An estimated 1,600 people have died.
The government says the international community has promised 92 million dollars, but it is the presence of US military helicopters that may incite the most controversy in Pakistan, where anti-Americanism is endemic.
The White House said that US helicopters have helped to save more than 1,000 lives in Pakistan. Washington has provided 35 million dollars in aid, including 436,000 halal meals and 12 pre-fabricated bridges.
"The primary focus of our mission is to provide food to people," Major Daniel Rice, commanding officer of the US aviation fleet in Pakistan, told AFP.
When asked whether it would help remove misunderstandings about the United States in Pakistan, he said: "I certainly hope so." "We are learning from each other every day... We are talking about each other's families as we deal together with the calamity here," Rice added.
Islamabad's alliance with Washington and the presence of nearly 150,000 US led foreign troops fighting the Taliban in neighbouring Afghanistan has been blamed within Pakistan for its own rise in militancy.
Concerned about anti-American sentiment, the Obama administration is trying to engage more fully with Pakistan, which has long seen Washington as interested only in securing its military cooperation in fighting terrorism.
Washington has earmarked 7.5 billion dollars in development aid over five years, but has sought to persuade Pakistan to widen its fight against militants to Taliban and al Qaeda linked groups who threaten US troops in Afghanistan.
A covert US drone war against Taliban and al Qaeda militants in Pakistan's semi-autonomous tribal belt has inflamed public sentiment in the northwest.
But on the ground, US troops say the experience of helping with flood aid has been only positive. After being grounded because of bad weather, helicopters flew sorties on Monday evacuating people and bringing food supplies to Swat.
"We are here to help people of Pakistan... Pilots have come back saying they saw lots of smiles, waving of hands and thumbs up while delivering supplies and shifting people to safer areas... and that is a good sign," said Rice.
The United States has sent four Chinooks and two Blackhawks to Pakistan, which fly with a representative of the Pakistani military on board. It is the second time since the 2005 earthquake, which killed more than 73,000 people and left around 3.5 million homeless, that the US government has sent helicopters to Pakistan for relief operations.
Authorities in Pakistan's northwestern Khyber-Pakhtunkhwa province have warmly welcomed the US assistance. "Floods have devastated the communications system in our province. US helicopters, in this crisis situation, have become a backbone in the relief operations," information minister Mian Iftikhar Hussain told AFP.
The lounge near the base's apron hummed with activity as pilots of the Pakistani and US armies sat together, exchanging pleasantries and gulping tea and coffee as it rained intermittently, with low visibility outside.
"Let people of Pakistan decide about our image as we deliver supplies and carry people from flood-affected areas," said US pilot George Kelly, adding that "very poor" weather was one of the main challenges.
Kelly said he was overwhelmed by the beauty of the Swat valley, calling the former trouble spot "probably the prettiest place I have ever come to".
The army has provided separate lodging to over 90 US military officials, who are closely in touch with air traffic for minute-to-minute weather updates.
"(The) Pakistan army offers a world class facility at the base and we received excellent support. We are really impressed to see the hospitality of our hosts," said a US army Major Marc Geeting.
Sergeant Curtis Hissong was equally upbeat. "It gives us satisfaction to deliver food supplies to Pakistanis stranded in different areas. "The biggest challenge for us is weather, and we are overcoming it as best as we can," Hissong said.
In flood-hit Kalam, Bahrullah Khan, 38, a teacher who has been stranded there since floods struck while he was on holiday, said the American help was a blessing. "Pakistani helicopters evacuate army people or people of their own choice. The US helicopters in this situation are really a blessing for us. "We can now expect we will also have our turn and will get an opportunity to leave soon," he said.