Ever since the United States went public on Tuesday with the Iranian plot, many have questioned the obvious lack of sophistication and the level of state sponsorship in the operation. Even if this alleged Iranian plot never came to light, however, the Saudis would still be facing the same strategic dilemma and constraints in dealing with its Persian neighbor.

Saudi Arabia is facing a nightmare scenario in the Persian Gulf. By the end of the year, the United States is scheduled to complete its troop withdrawal from Iraq, and whatever troop presence the United States tries to keep in Iraq past the deadline will not be enough to convince anyone, especially Saudi Arabia and Iran, that the United States will be able to prevent Iran from emerging as the dominant force in the Persian Gulf region. These next few months are therefore critical for Tehran to reshape the politics of the region while the United States is still distracted, Turkey is still early in its rise and Iran still has the upper hand. Iran can only achieve this goal of regional hegemony if it can effectively exploit the vulnerabilities of its Arab neighbors — especially Saudi Arabia — who are extremely unnerved by the thought of the United States leaving behind a power vacuum in the region for Iran to fill.

Iran’s main strategic intent is to convince the United States and Saudi Arabia that there is no better choice but to reach an unsavory accommodation with Tehran, one that would be negotiated in Iran’s favor and grant Tehran the regional legitimacy it’s been seeking for centuries. The Saudis want to prevent this scenario at all costs, and so can be expected to do everything it can to show Washington that Iran is too dangerous to negotiate with and that more must be done by the United States to keep Iran contained behind its mountain borders. Purported Iranian plots aimed at assassinating Saudi diplomats certainly help underscore that message, but there is still little hiding the fact that the United States simply doesn’t have good options in dealing with Iran in the near term.

The United States doesn’t have the resources to devote to blocking Iran in Iraq, or engaging in military action against Iran. In today’s fragile global economic environment, the Iranian retaliatory option of mining and attempting to shut down the Strait of Hormuz, through which 40 percent of the world’s oil trade passes through each day, remains a potent deterrent. In describing how it intends to hold Iran accountable for this alleged assassination plot, the White House has focused on increased sanctions, but by now it should be obvious that Iran will find ways to insulate itself from sanctions and continue its day-to-day business with a multitude of shell firms looking to make a profit in trading with Iran at higher premiums.

Given that the United States is Saudi Arabia’s main security guarantor, the lack of U.S. options means that Saudi Arabia also has very few, if any, good options against Iran in the current threat environment. Saudi Arabia’s best geopolitical weapon is its oil wealth, but even the threat of flooding the oil markets to cut into Iran’s own oil revenues carries its fair share of complications. Saudi Arabia claims that it would take 30 to 60 days to reach a maximum level of output around 12.5 million barrels per day, but they would have to sustain that level of production for an extensive period of time in today’s depressed market to begin to make a serious dent in Iran’s oil income. There are already questions about whether Saudi Arabia has the capability to surge production on this scale, not to mention the complications it would face from other oil producers that would also suffer the consequences of an oil flood in the markets. So far, there hasn’t been any indication that Saudi Arabia is prepared to go this route in the first place.

Saudi Arabia also has the more traditional option of backing dissidents and Sunni militants in Iran, Iraq, Lebanon and Syria in an effort to undercut Iran’s growing influence in the region, but engaging in a full-fledged proxy battle with Iran also carries major implications. Of most concern to Saudi Arabia is Iran’s likely covert response along the eastern littoral of the Arabian Peninsula. Saudi Arabia is already extremely concerned with the situation in Bahrain, where it fears growing Shiite unrest will cascade into Saudi Arabia’s oil-rich, Shiite-concentrated Eastern Province. Iran’s capabilities in this region are more limited relative to its covert presence in Iraq and Lebanon, but the Saudi regime is on the alert for signs of Iranian prodding in this tense Sunni-Shiite borderland. A rare security incident in Qatif in Saudi Arabia’s Eastern Province Oct. 3 clearly highlighted this threat when a group of Shiite rioters reportedly shot automatic weapons at security forces.

Saudi Arabia has every interest in trying to convince Iran in the coming months that Riyadh has the will, capability and U.S. support necessary to respond to any Iranian act of aggression. The reality of the situation, however, reveals just how constrained the Saudi regime is in trying to contain their historic Persian rivals.