Washington (CNN) -- Four additional U.S. Marine Corps CH-46 helicopters arrived Monday in Pakistan, bringing to 11 the total number of U.S. helicopters there to help with flood-relief efforts, the Pentagon announced.
The U.S. military has ordered a total of 19 helicopters to Pakistan, so more are on the way.
Also, two C-130 aircraft started flying Monday inside the country, transporting international aid.
"We've continued to increase our level of support and commitment to the relief operations there," Pentagon spokesman Bryan Whitman said.
The Pentagon expects the flights to deliver 52,000 pounds of relief supplies, focused on the Sukkur district of Sindh province in northern Pakistan. From there, it's supposed to be distributed to needy people by Pakistani authorities and military.
Since August 5, American troops have rescued more than 3,500 people and transported more than 436,000 pounds of relief supplies, officials said.