Intermittent electricity, informal payments and a low-skill labor force are all major constraints to doing business in Cambodia, the report says.
But analysts say Cambodia's long-term attractiveness to US investors will depend on long-promised reforms, particularly in education, energy security and anti-corruption.
Sen. Don Benton, from Washington state, told VOA Khmer that Cambodia has many business opportunities, compared to other Asean countries.
Forestry activists say at least 55,000 tons of luxury wood has been sent from Cambodia to China this year alone.
Major brands who source from Cambodia have meanwhile begun to push for fair conditions and wages for factory labor.
John Kerry speech marked the 30th anniversary of the US-Asean Business Council and comes as Asean is moving toward economic integration in 2015.
More than 1,000 people marched on the National Assembly on Monday, many of them displaced from land disputes, to mark World Habitat Day.
Workers have begun midday strikes in support of a wage increase to $177 per month, an amount factories have said they cannot afford.
Cambodian Foreign Minister Hor Namhong is slated to deliver a speech to the UN’s General Assembly on Monday in New York.
A general view of daily activities of residents at Phnom Penh's White Building on Friday, September 5, 2014. (Nov Povleakhena/VOA Khmer)
The unions want a raise for workers to $177 per month, to keep up with the higher costs of living in Cambodia.
A general view of Phnom Penh's White Building, known locally as the "Building" and its residents on Friday, September 5, 2014. (Nov Povleakhena/VOA Khmer)