Israeli news outlet Debka reported that Iranian engineers have been working almost nonstop to expand the range of the Scud C (400 miles) and Scud D (450 miles) surface missiles by an additional 60 miles, enabling the projectiles to reach Riyadh.
The so-called Riyadh project was ordered by Iranian President Hassan Rouhani and Supreme leader Ayatollah Ali Khamenei, and was developed near Tehran at the Al Ghadi base.
In referring to the Riyadh Project, Amir Ali Hajizadeh, air force commander for the Islamic Revolutionary Guard Corps (IRGC), remarked earlier in February that, "Should the enemy make a mistake, our roaring missiles will rain down on them."
Iran’s General Hajizadeh heads the missile-testing site and has ordered other efforts stopped to focus solely on the Riyadh Project.
In early February Houthi opposition militants in Yemen claimed that they launched a homemade Borkan missile with a 500-mile range west of Riyadh, striking the Mazahimiyah military camp. But the Houthi faction reportedly does not have a missile with that range capability, and were thought to actually be testing an enhanced Iranian scud missile for use in future strikes.
A Houthi government official said afterwards, "We stress that the capital of Saudi Arabia is now in the range of our missiles and, God willing, what is coming will be greater," according to Al Araby.
A confirmation of Humaidan’s visit would indicate that he is attempting to parse security issues concerning a regional conference with the US and the Israeli-Arab areas while in Jerusalem, and warning Palestinians not to strengthen ties with Iran while visiting Ramallah. The conference was proposed during a February 15 meeting between Israeli Prime Minister Benjamin Netanyahu and US President Donald Trump.
In August 2015, the Jerusalem Post reported that Palestinian President Mahmoud Abbas delivered a letter to Rouhani detailing the "Israeli assaults against our people and their holy sites, as well as bilateral relations between the two sides."