President Barack Obama included $4 billion to improve security at hundreds of overseas diplomatic posts in his budget proposal on Wednesday, in the wake of the deadly September 11, 2012, attacks on the U.S. mission in Benghazi, Libya.

The money would secure overseas personnel and facilities, including enough money to increase embassy security construction to $2.2 billion, as recommended after an independent review of the Benghazi attacks.

Embassy security has been under particular scrutiny - amid harsh criticism of the Obama administration by Republican lawmakers - since the U.S. ambassador to Libya and three other Americans were killed in the eastern Libyan city.

The proposal reflects shifting U.S. priorities as Washington winds down its wars in Iraq and Afghanistan. Programs in Iraq, Afghanistan and Pakistan account for $6.8 billion of the budget proposal, $4.2 billion less than requested in 2012. The budget plan calls for $2.1 billion for Iraq, $3.4 billion for Afghanistan and $1.4 billion for Pakistan.

"We owe it to the American people to do our part to help solve the fiscal problems that threaten not only our future economic health, but also our standing in the global order," Secretary of State John Kerry wrote in a letter to Congress.

"As such, we have proposed necessary cuts, where it will not adversely affect our national security, and we propose modest increases, where they are necessary to achieve our highest priorities," he said.

Overall, Obama has asked for $47.8 billion for the Department of State and U.S. Agency for International Development, a six percent decrease from 2012 levels, because of the lower requests for Iraq and Afghanistan.

As expected, the budget proposes the most sweeping change in U.S. food aid in decades, with a plan intended to feed more people and deliver food more quickly. It would end a practice of buying food from American farmers and shipping it overseas.

Under the plan, Washington would donate $1.1 billion to a disaster relief account for food vouchers that would be used to buy food from suppliers located near areas of need.

Shipping can double food aid costs because, by law, supplies must be transported on U.S.-flagged vessels.

An additional $250 million would be provided to economic development projects and $75 million would be earmarked for emergency relief.

The food aid proposal could face a tough fight. Aid groups disagree over whether the switch to cash donation is advisable. And two dozen senators wrote the White House in March to try to derail the change.

However, proponents said the plan would let the United States feed millions more people each year, while assisting farmers in poor countries by buying their crops.

(Reporting by Patricia Zengerle; Editing By Marilyn W. Thompson and Paul Simao)