On October 18, U.N. sanctions on Iran buying or selling weapons lapsed, in spite of a high-profile U.S. effort to extend them. What actions Iran will take going forward is a matter of great concern in the region. Iran’s defense establishment has not been gutted by sanctions, but it has been severely degraded in several key areas. So, what will Iran choose to buy?

First, while various branches of Iran’s security services may have their own wish lists, the dire economic situation in the country and the continued effectiveness of U.S. sanctions will force Iran’s leaders to make tough decisions. For example, Iran’s air force may wish to recapitalize with the latest Russian air-to-air fighter jets, but such an expensive ambition is out of the question for the foreseeable future given economic constraints.

Similarly, while Iranian ground forces may wish to build a large fleet of modern tanks, such as the Russian T-90 battle tank, it is unlikely Iran can afford to buy more than a token force. It is possible that Iran will buy a small number of modern fighter aircraft and modern tanks just to show it can – almost as a celebratory measure – and hope to use these as a core for future expansion when its financial situation improves.

A second factor weighs against Iran buying a large number of conventional weapons: Iranian strategic culture. The horrors of the Iran-Iraq War still weigh heavily in Iranian strategic thought, and Iran’s leaders know an outright conventional challenge against the United States and its coalition partners would lead to disaster. So, Iran has focused on developing and procuring asymmetrical weapons, not conventional ones. For airpower, this means Iran buys missiles, not manned aircraft. For land power, this means proxy forces, not armored divisions. This asymmetric strategy avoids confrontation with the overwhelming conventional power of the United States and its partners. This strategy will not change with the lifting of sanctions. So, Iran won’t buy expensive Russian jets to match the more expensive jets of the Emiratis or Saudis – it will continue to rely on missiles and drones for long-range strikes. Iran will keep pursuing its security goals by other means: low cost, unattributable assets such as naval mines, drones, ballistic missiles, and proxy forces.

Iran also has a relatively self-sufficient defense industry with a skilled workforce. While it is not capable of manufacturing revolutionary weapons on its own, it has proved to be more than capable at reverse engineering and then making incremental refinements to purchased weapons, such as missiles. This factor, combined with Iran’s financial constraints and strategic culture, means that most of the big purchases will be either complex weapons systems that Iran cannot manufacture on its own or components that will enhance and augment existing capabilities.

With that in mind, Iranian imports can be expected to fall into two categories: complete systems to counter U.S. capabilities (such as aircraft carriers) and components and enabling weapons (such as jamming and anti-jamming systems) that enhance existing Iranian capabilities.

There are two main areas where Iran is likely to buy off-the-shelf weapons systems: air defense and anti-ship systems. Both of these capabilities are firmly aimed at U.S. dominance in the air and at sea.

In air defense, Iran will likely press for the state-of-the-art Russian S-400 anti-aircraft system. The S-400 is an incremental improvement over Iran’s already fielded S-300 system, so the burden of training and maintenance will be minimized. As this is a defensive system, it was not prohibited under the U.N. sanctions. However, in response to U.S. requests, Russia did delay for some years in exporting the S-300 and will probably be more eager to sell the S-400 now that sanctions have expired. While the efficacy of the S-400 has been called into question by Israel’s ability to conduct airstrikes in Syria, Israel has not directly challenged the Russian S-400 system and appears to have conducted most of its operations in areas defended only by Syrian air defenses, which rely on the earlier S-300. The S-400 still remains the best available option for countering U.S. airstrikes.

In coastal defense, Iran will likely purchase entire systems aiming to deny access to U.S. and coalition warships, particularly aircraft carriers. U.S. aircraft carriers positioned in the Gulf remain a significant component of the United States’ ability to attack Iran’s homeland. The Russian Bastian coastal defense system, which features a sea-skimming, hypersonic missile that can operate in a jamming environment, could be at the top of Iran’s shopping list; a similar Chinese system (such as the DF-21 “carrier killer”) may be under consideration as well.

The second major area of expected Iranian weapons purchases is enablers and components. While Iran has an active engineering culture in its defense industries, some areas are still out of reach. Solid fuel rocket motors are sometimes still imported, and Iran can be expected to look to Russia for electronic warfare systems, precision guidance electronics, secure and hardened communications systems, and other defense components that require a defense science base, which only a few countries have. The net result of these purchases would be more reliable and accurate Iranian missiles, together with the ability for Iran to conduct synchronized strikes with ballistic missiles, cruise missiles, drones, and artillery in an electronically contested battlespace.

Because of Iran’s shattered economy, strategic culture, and generational commitment to asymmetric warfare, it is unlikely Tehran will seek to build a large conventional military force. To do so would put Iranian capabilities into the forefront and draw more attention to Tehran’s actions. Such a move would be more visible than, say, the acquisition of components to improve ballistic missile guidance and thus more likely to provoke Gulf Arab and U.S. countermeasures.

Instead, Iran will do as it always has – seek to quietly develop asymmetric capabilities, ideally built domestically, and only purchase the few items that it cannot make hoping to counter key U.S. military capabilities. Iran will not field a major force of Russian tanks in the near term – instead, it will continue to direct militias while hoping to build ever-widening zones of exclusion to keep U.S. ships and airplanes at bay.