The head of Germany's largest weapons manufacturer believes that tension between Berlin and Ankara is making it virtually impossible for his company to conduct business with Turkey.

German arms producers are required to gain authorization from the Economy Ministry to sell their products and services abroad. "If relations with Turkey don't improve, it will be difficult to get any permissions from Germany," Rheinmetall CEO Armin Papperger told the news agency dpa in an interview published on Sunday, complaining that a number of bilateral military hardware projects are on ice.

Weapons are a major, if very controversial, German industry. A decline in sales to Turkey might put a dent in the larger numbers, but it appears that German arms manufacturers have plenty of potential clients.  

How large is Germany's arms trade with Turkey?

In response to an official inquiry, in September the Economy Ministry reported that it had approved about €25 million ($30 million) in arms sales to Turkey in the first eight months of 2017. That was down from €69 million in the same period of last year. According to the ministry, the approved exports primarily consisted of bombs, torpedoes and missiles.

By way of comparison, in just the first four months of 2017, Sweden had received €30.6 million worth and Switzerland €22.7 million.The top two customers, Algeria and Lithuania, bought €830 million and €469 million worth, respectively.

Where does Germany stand among the world's arms exporters?

You'll often hear Germany referred to as the world's third-leading weapons seller, but official statistics are usually neither completely reliable nor completely up-to-date. What seems certain is that Germany is in the top five, well behind the United States and Russia, with sales volumes more comparable to those of China and France.

The government granted permission for arms sales valued at €6.85 billion in 2016. Last year, Germany accounted for around 5.6 percent of the world's weapons exports, according to the Stockholm International Peace Research Institute.

Germany has a broad customer base, exporting arms to dozens of different countries, including the US, the UK, Greece, Brazil, South Korea and India. According to the government, 46.4 percent of permissions for German arms sales were for fellow NATO countries, including Turkey.

Are German exports on the rise or decline?

That depends on how you look at the situation. Weapons demand dramatically increased in 2015, largely from countries in the Middle East and Northern Africa, so currently German export levels remain comparatively high. The trade publication Jane's Defence estimates that the Middle East and North Africa could account for 40 percent of German arms exports by 2018, which is comparable with those two regions' share in the global market.

If you look at a narrower time frame, German weapons exports are declining. The €6.85 billion estimated in 2016 represented a significant decrease over the record €7.86 billion in 2015. And the official export approval figures for the first four months of this year (€2.42 billion) are also significantly down on those from the same period in 2016 (€3.3 billion).

Fewer permissions for arms sales have been issued as the government has focused increased attention on potential buyers. In 2013, Germany pledged to reduce the amount of arms it exported after widespread criticism.

What other German arms sales have stirred up controversy?

Germany has provided weapons to a number of countries with dubious human-rights records, including both Saudi Arabia and Qatar, which engaged in a tense standoff over the summer. German arms sales to Egypt and the United Arab Emirates, both countries accused of commonly using torture, have also been criticized.

Though it was ultimately approved, a submarine deal with Israel worth an estimated €1.5 billion came under fire earlier this year following allegations of corruption in Israel. In the past, critics have noted that German submarines sent to Israel could be modified to carry nuclear missiles.