RIYADH: Saudi Arabia’s King Salman received a letter from US President Joe Biden to congratulate the Kingdom on its National Day, Saudi Press Agency reported on Thursday. Biden extended his best wishes to the king and praised the permanent relations between the two countries that spanned over eight decades, which remains a cornerstone of stability, security and economic prosperity in the Middle East. The US president said he looked forward to continuing joint work in many fields. Saudi Arabia marked its 91st National Day on Sept. 23 with nationwide celebrations.