Images analysed by experts at IHS Jane's Intelligence Review has revealed a hitherto undisclosed surface-to-surface missile base deep in the Saudi desert, with capabilities for hitting both countries.
Analysts who examined the photos spotted two launch pads with markings pointing north-west towards Tel Aviv and north-east towards Tehran.
They are designed for Saudi Arabia's arsenal of lorry-launched DF 3 missiles, which have a range of 1,500-2,500 miles and can carry a two-ton payload.
The base, believed to have been built within the last five years, gives an insight into Saudi strategic thinking at a time of heightened tensions in the Gulf.
While Saudi Arabia does not have formal diplomatic relations with Israel, it has long maintained discreet back channel communications as part of attempts to promote stability in the region.
The two countries also have a mutual enemy in Iran, though, which has long seen Saudi Arabia as a rival power in the Gulf. Experts fear that if Iran obtains a nuclear weapon, Saudi Arabia would seek to follow suit.
Analysts at IHS Jane's believe that the kingdom is currently in the process of upgrading its missiles, although even the DF3, which dates back to the 1980s, is itself potentially big enough to carry a nuclear device.
The missile base, which is at al-Watah, around 125 miles south-west of the Saudi capital, Riyadh, was discovered during a project by IHS Jane's to update their assessment of Saudi Arabia's military capabilities.
It serves as both a training and launch facility, with the missiles stored in an underground silo built into a rocky hillside. To the north of the facility are two circle-shaped launch pads, both with compass-style markings showing the precise direction that the launchers should fire in.
The Chinese-made missiles, which date back to the 1980s, are not remotely-guided and therefore have to be positioned in the direction of their target before firing.
"One appears to be aligned on a bearing of approximately 301 degrees and suggesting a potential Israeli target, and the other is oriented along an azimuth (bearing) of approximately 10 degrees, ostensibly situated to target Iranian locations," said the IHS Jane's article, which is published on Thursday.
While the lorry-launched missiles can theoretically be fired from any location, the idea of having pre-planned directional markers is to ensure that they can be deployed in accurate fashion as quickly as possible, said Allison Puccioni, an image expert at IHS Jane's.
"There is a marked out spot for the launch truck to park in, which will facilitate an expedited launch," she said.
Robert Munks, deputy editor of IHS Jane's Intelligence Review, said: "Our assessment suggests that this base is either partly or fully operational, with the launch pads pointing in the directions of Israel and Iran respectively. We cannot be certain that the missiles are pointed specifically at Tel Aviv and Tehran themselves, but if they were to be launched, you would expect them to be targeting major cities.
"We do not want to make too many inferences about the Saudi strategy, but clearly Saudi Arabia does not enjoy good relations with either Iran or Israel."
Officials at the Saudi Embassy in London did not get back with a response when contacted by The Telegraph. The Israeli Embassy in London said: "We have no comment on this matter."
David Butter, an associate fellow with the Middle East and North Africa program at Chatham House, the London-based foreign affairs think-tank, said there was "little surprise" that the Saudis had the missiles in place.
"It would seem that they are looking towards some sort of deterrent capability, which is an obvious thing for them to be doing, given that Iran too is developing its own ballistic missiles," he said.
He added, though, that the Saudis would know that the site would come to the attention of foreign intelligence agencies, and that the missile pad pointed in the direction of Israel could be partly just for "for show".
"It would give the Iranians the impression that they were not being exclusively targeted, and would also allow the Saudis to suggest to the rest of the Arab world that they still consider Israel a threat."
Oil-rich Saudi Arabia considers itself one of the pre-eminent powers in the Gulf region, but its Sunni Islam leadership has long been at loggerheads with the Shia mullahs of Iran.
The ongoing conflict in Syria, which Saudi Arabia has backed the Sunni-dominated rebels and Iran has backed the Shia-dominated regime of President Bashar al-Assad, has heightened fears of a wider sectarian conflict.
A confidential diplomatic cable revealed in the "WikiLeaks" disclosures of 2010 said that King Abdullah of Saudi Arabia repeatedly exhorted the United States to launch military strikes against Iran's nuclear programme and "cut off the head of the snake"