Since 2015, Russia has made inroads into the Middle East in a way that few could have imagined at the time. While Moscow's military intervention in Syria has served to prop up the regime of Syrian President Bashar Assad, it has also allowed it to show off its military might.

One of the knock-on effects has been a growing interest in Russian military hardware, most notably the S-400 anti-aircraft missile system.

"The demand is rather significant after the Syrian events," Alexander Mikheyev, chief executive of Russian weapons exporter Rosoboronexport, told state-owned news agency TASS last week.

'Russian moment'

Part of the interest from US allies in the region, including Saudi Arabia, Qatar and Turkey, stems from waning American leadership, Fawaz Gerges, international relations professor at the London School of Economics, told DW.

"This is a Russian moment," said Gerges. The Lebanese-American academic noted that instead of showing leadership, US President Donald Trump's administration had done quite the opposite by highlighting the "great differences between the United States and its Western allies."

The differences have been most notable with Turkey, a NATO member that has signaled its intention to buy the Russian anti-aircraft weapon system. Turkish President Recep Tayyep Erdogan on Friday said his country "needs S-400" and would move to "buy them as soon as possible."

Turkish President Recep Tayyip Erdogan's announcement that Turkey would be buying military hardware from Russia caused a stir across the NATO alliance

'Unresolved contentions'

Relations between the US and Turkey have deteriorated over the detention of an American pastor, with Congress in July blocking the delivery of F-35 fighter jets that Ankara had already partly paid for.

"There are clearly a series of unresolved contentions at the domestic, regional and international levels that are contributing to this search for security," Robert Mason, director of the Middle East Studies Center at the American University in Cairo, told DW.

But while Turkey is still intent on acquiring Russian military hardware, Saudi Arabia appears to have let go of the prospect. Colonel Konstantin Sivkov, vice president of the Russian National Geopolitical Academy, told Russian broadcaster RT that Saudi Arabia had "succumbed to pressure from the United States," according to the London-based Middle East Monitor.

"The US needs to engage in more robust diplomacy to reassure allies and adversaries, which are engaged in a Middle East Cold War," added Mason, a former visiting scholar at the Jordan Center for the Advanced Study of Russia at New York University.

Other US allies in the region reportedly in talks to acquire the Russian S-400 system include Iraq and Morocco.

'Russian system outperforms'

But politics are only one dimension of US allies' interest in Russian military hardware.

Egyptian Brigadier General Samir Ragheb, president of the Arab Foundation for Development and Strategic Studies, told DW that in many ways, countries in the region view the S-400 system as a better alternative to the Patriot system, the US alternative.

"There is no doubt that this Russian system outperforms the Patriot system in range and ability to deal with targets in a small orbit, and its ability to launch multiple missiles," Ragheb said.

Read more: Is Russia challenging US military dominance?

Experts have also noted that Washington's issue with the system could stem from its technological capabilities.

"The root cause of US dissatisfaction appears to be the S-400 missile defense system's ability to track and destroy aircraft at unprecedented ranges and to gather information about aircraft in the surrounding airspace," Mason told DW.

The Economist news magazine described the S-400 as "one of the best air-defense systems currently made"

'Serious downsides'

The US has warned that it would not stand idle when it comes to countries acquiring military hardware from Russia.

The US State Department threatened on multiple occasions to target countries making substantial purchases from Russia's defense or intelligence sectors, citing potential penalties through the Countering America's Adversaries through Sanctions Act (CAATSA) of 2017.

US Ambassador Tina Kaidanow, who serves as acting assistant secretary of the Bureau of Political-Military Affairs at the State Department, said in July that the White House wants US allies to understand how serious the White House is when it comes to them acquiring Russian military hardware.

"We want them to understand the downsides, the real, serious downsides to making these acquisitions, and particularly the S-400 acquisitions from the Russians, and to continue to … look to our systems and to put inter-operability and all the other things we care about first," said Kaidanow.

Read more: Russian money flows into Germany despite sanctions

'Project influence'

Richard Nephew, senior fellow at Washington-based Brookings Institution and former Obama administration official for sanctions policy at the US State Department, told DW that US allies could also face problems attempting to incorporate the S-400 system into their arsenal.

"My understanding is that integrating US and Russian military hardware isn't seamless and, therefore, it would be complex to do so," Nephew said. "If such sales are successful though, then I think the biggest issue would not be from proliferation, but rather from increased Russian operations with those allies."

With an increased presence in the region, Moscow would be making headway with its strategy, Daniel Byman, senior fellow in the Center for Middle East Policy at the Washington-based Brookings Institution, told DW.

"It is a way for Russia to project influence, showing that Moscow — not Washington — is a player in the region that will deliver security for those who choose to be its friends."

Watch video 26:05 Philip Breedlove on Conflict Zone

Every evening at 1830 UTC, DW's editors send out a selection of the day's hard news and quality feature journalism. You can sign up to receive it directly here.