US President Donald Trump (L) met Saudi Arabia's King Salman bin Abdulaziz al-Saud (2nd-R) on his first foreign visit in 2017
AFP

Saudi Arabia plans to invest $600 billion in the United States over the next four years.

A state-run agency revealed the announcement from Crown Prince Mohammed bin Salman after his phone call with President Donald Trump, according to the AFP.

The pledge aligned with Trump's previous efforts to strengthen economic ties with Saudi Arabia, including his 2017 visit to Riyadh.

The visit was the catalyst for a yearslong boycott of Qatar by four Arab nations.

The investment could include U.S.-made weapons, defense systems, and ventures funded through the sovereign wealth fund.

After his inauguration, President Trump said he may visit Saudi Arabia as his first foreign trip.

The announcement comes as Saudi Arabia faces economic challenges.

An investment climate statement by the U.S. Department of State revealed the country is seeking foreign investment including infrastructure.

Saudi Arabia needs funding for projects like NEOM, a new city being built near the Red Sea, and infrastructure for the 2034 FIFA World Cup amidst a shrinking global demand for oil.

Last year, President Joe Biden's administration offered to help defend Saudi Arabia from Iranian threat.