The US State Department has approved the sale of $1.29 billion (£848.6m) worth of bombs to Saudi Arabia, as its military carries out air strikes in neighbouring Yemen.
President Obama pledged to bolster military support for Saudi Arabia after tensions were strained following a US-brokered nuclear deal with Iran.
The US Congress now has 30 days to stop the deal if it wishes to do so.
Saudi Arabia is one of the biggest buyers of US weapons.
The Saudi-led campaign against Iran-backed Houthi rebels in Yemen has drawn criticism, with several reports of civilian casualties on the ground.
Washington has backed the campaign and Saudi Arabia – who is a central ally in the air assault against the so-called Islamic State group in Syria and Iraq.
US-Saudi ties are said to have been strained by Mr Obama’s unwillingness to take military action against Syria’s President Bashar al-Assad, and his support for a nuclear deal with Iran that the Saudis fear will ultimately allow Iran to acquire nuclear weapons.
The sale, if it is not blocked by the US congress, “will replenish the Royal Saudi Air Force’s (RSAF) current inventory, augmenting Saudi Arabia’s capability,” a State Department spokesman said.
In May, King Salman skipped a summit of Gulf Arab leaders at Camp David, which was widely interpreted as a snub for the US president.
However, relations seemed to warm after Saudi King Salman’s visit to the Washington in September.
Saudi Foreign Minister Adel al-Jubeir said his country was satisfied that the deal would contribute to security and stability in the Middle East.