Russian President Vladimir Putin signed a key deal Monday with Saudi Arabia during a key visit for an OPEC+ grouping aimed at stabilizing global oil prices and seeking to calm regional tensions with Iran.

Following talks between Putin and Saudi King Salman, the two countries signed some 20 agreements and contracts worth billions of U.S. dollars on aerospace, culture, health, advanced technology and agriculture.

Putin noted that the Saudi Arabian Public Fund has allocated 10 billion U.S. dollars for joint foreign direct investment projects in Russia, a statement said on the Kremlin's website.

The president said Russia "attaches particular importance to the development of friendly, and mutually beneficial ties with Saudi Arabia."

King Salman said his country looks forward to working with Moscow "on everything that will bring security, stability and peace, confront extremism and terrorism, and promote economic growth."

Monday's deal seeks to "reinforce cooperation... and strengthen oil market stability," Saudi Energy Minister Prince Abdulaziz bin Salman said at the signing ceremony.

The two also discussed "bilateral cooperation" and development in Syria and Yemen.

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Is Russia widening its footprints in the Middle East?

Moscow and Riyadh, a traditional U.S. ally, have made a striking rapprochement in recent years, marked in particular by King Salman's first visit to Russia in October 2017, when Russia and Saudi Arabia signed a memorandum of understanding paving the way for Riyadh's purchase of Moscow's powerful S-400 anti-aircraft missile systems. 

The sale never materialized, however, as Saudi Arabia eventually opted to purchase a U.S. system.

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Will Putin succeed in selling Russia's S-400 to Saudi Arabia? 

After Saudi Arabia, Putin will travel to the United Arab Emirates on Tuesday to meet the crown prince of Abu Dhabi, Mohammed bin Zayed Al-Nahyan.