Having carried out aerial sorties in Yemen and Syria over the past year, Saudi Arabia has struck a $1.3bn (€1.2bn) deal to replenish its depleted stocks of smart munitions. Following approval from the US Department of State, the Royal Saudi Air Force will receive 22,000 smart and general-purpose bombs from either Boeing or Raytheon.

The sale is a reassurance from the US that it will continue to support Saudi Arabia after the nuclear agreement between world powers and Iran. The leadership in Riyadh is worried that Tehran now has a free hand to undermine the sovereignty of states with Shia populations across the region; there are also fears that this could spread what Saudi Arabia deems a dangerous revolutionary ideology. The decades-old rivalry has been exacerbated by the ongoing conflict in Syria and recently in Yemen, where Saudi Arabia launched military operations to oust pro-Iranian rebels who took over swathes of the country last year.

“Essentially the commitment to providing the kingdom with the new arms package is to send a signal that the US is still committed as an ally to Saudi Arabia,” says Michael Stephens, research fellow for Middle East studies at the Royal United Services Institute. “From Saudi’s point of view the key is to send a message to Tehran that their activities across the region will be resisted, by force if necessary.”

The US supply of munitions has been criticised by human-rights groups who accuse the administration of helping Saudi Arabia perpetrate a war in Yemen. In November the UN estimated that the conflict had left more than 5,000 civilians dead to date. That figure is set to rise, according to analysts.

But there is big business behind what is one of the most significant defence relationships in the world; it’s a boon for the US defence industry. Having bought $90bn (€82bn) in armaments and weapons systems from the US since 2010, Saudi Arabia is its biggest customer.

An airfield from a dark chapter of Spain’s past has been earmarked for the aircraft of the future. Built by the Nazis in 1943 in Castro de Rei, along Spain’s northern coast, the airfield will be transformed into one of Europe’s largest drone research centres: the Rozas Aero Transport Research Center.

Jointly funded with €55m from the Galician government and the Spanish Ministry of Defence’s National Institute for Aerospace Technology, authorities plan to lease ground and airspace to multinational companies that are looking to explore new uses for unmanned aircraft. Critics have questioned the use of public money for a venture that will largely benefit the private sector. EU funding regulations prohibit the centre from solely dedicating its research to military purposes but can’t control the ultimate application of the technology to the battlefield.

The UK is set to have a 21st-century air force sooner than anticipated. The country’s most recent defence review saw an announcement that it would have 24 Lockheed Martin f-35s in operation by 2023, instead of the eight it had initially proposed in that timeframe.

“They take a different approach to the traditional fighter,” says Justin Bronk, research analyst at the Royal United Services Institute. “It’s a very information-centric system.” They are nevertheless expensive, at upwards of £100m (€140m) per aircraft. Yet if the vote in favour of airstrikes in Syria is any indication, the purchase is in line with the country’s vision for its forces.

Ukraine’s government has signed a preliminary deal with China to acquire Hongdu l-15 Falcon jet trainers for its air force. The move marks another step by Kiev to replace Russian-designed military gear with domestic production in the aftermath of Moscow’s military intervention in the Crimean peninsula.

The Ministry of Defence told journalists that the jet trainers will be made at the Odessa Aviation plant and production could be launched in 2016. The supersonic aircraft is able to serve as both a trainer and a light-attack machine.