Iraq and Saudi Arabia ...... only
Iraq
No, Saudi Arabia is a completely different country. But, Iraq borders it to the North.
Saudi Arabia.
Kuwait.
The State of Kuwait is the smallest country that is bordered by both Saudi Arabia and Iraq. Kuwait shares its southern border with Saudi Arabia and northern border with Iraq.
Saudi Arabia
There are two countries directly between Iraq and Saudi Arabia: 1. Kuwait, 2. "Iraq-Saudi Arabia neutral zone" - which ended in 1990 as it was split between the two nations.
Kuwait and Jordan share borders with both Iraq and Saudi Arabia.
Saudi Arabia
Jordan.
Saudi Arabia is much bigger than Iraq.