But not that big a market
The important thing is the overall Russian yearly arms exports have been continuously rising since the 1990s, from some 2 bn to almost 10 bn. This steady growth is a result of pursuing "technical cooperation" partnerships, rather than one-time deals. If a country buys a product, it will need to train personnel, maintain it, get ammo and spare parts and eventually get a replacement. Russians offer full service and thus are their arms sales more resistant against shocks like purchase cancellations.
As mentioned above Russia is going to be part of the trade route between europe and asia, so it would make sense for them to try to replace some of that traffic with their own products in both directions and take advantage of their geographic location in the middle.
Another problem are tariffs. In a country leaning westwards, there will be little interest to reduce them in the middle of the sanctions hysteria.
For Russian companies it is important to diversify in areas that make sense.
The choice of areas will determine how successful the diversification is. It should be exactly oppositely correlated with primary activity. So if a company is in agriculture, its revenues drop when there's no rain. On the other side, when the weather is hot and dry more tourists come on vacation, so the firm could buy a vessel and offer tours.
Does the job, but not over engineered and not too expensive or too complicated.
Generally speaking, the simpler the product, the more competition you have. Developed countries like Russia have too expensive labour force to compete in the cheap products markets with developing countries. Vietnam used to be world's textil factory, now it's making cars. Mid priced clothes come from the least developed Asian countries - Cambodia and Bangladesh. Russians are fortunate enough to have developed heavy industry in the Soviet era and now don't have to worry about survival on export markets, because there's little to no competition when it comes to e.g. cheap SSKs, NPPs, aircraft, space rockets etc.
it is expensive to make so when they sell it for billions of dollars, that is not all profit
On the macro level, the GDP of a country can increase either with investment of with consumption. If S-400 producer payed low salaries and made a big profit, the profit would go to stakeholders, who would keep it in a bank for some interest rate. If 5 bn are salaries alone and the company has no profit, workers spend more money in the shops, then business owners maybe use the extra cash to renovate the place, which means business for construction workers. It goes on and on, increasing the GDP. State companies in Russia or China usually don't focus so much on profitability. They care more about the long-term stable growth and not firing the workers when there's less demand and they aren't profitable. Because more unemployment means more uncertainty about future and less purchases of durable goods, which in turn hurts companies and like a virus spreads from one sector to the other until the whole economy is in a recession. Russian economy proved to be much more resilient against the 2008 recession than the west.
EU at the moment is a sanction imposing, inflexible mess that wont negotiate and wont bend
The fact that the US and EU are dreaming about keeping world dominance, rather than getting real and talking with Russia and China, shows that western liberalism offers little answers for the 21st century challenges. Most the EU is now after a populist and anti-establishment alternative, whether it's Orban in Hungary or Conte in Italy. Further EU integration will be possible only with fresh ideas that will be able to deal with problems like Syria more independently from the US and taking into account Russia and China.
trump doesn't know what trump wants
His anti-interventionalism surely represents the exhaustion from blood and costly wars of the majority of the US people. The interests of the military and industry are also proving to be difficult to ignore. The point is however, without clear vision and 100 % determination, you can't win a smallest battle. They can send few thousand advisors to a hundred conflicts, so the companies continue manufacturing ammo, but they won't get anything done their way.
Still, even in afghanistan, Russian negotiations seem the most effective and practical in finding a solution there.... no thanks to the Americans.
If the US actually gets out, Russia will have to get more engaged. Neighbouring Tajikistan is in the CSTO, so if they have a problem, Russia has a problem. But hand on heart, no matter how serious that conflict is, it's not as complicated as Syria.
Sorry... Jamestown.org?
Russian bilateral diplomacy allows them to visit a country and focus on various aspects of cooperation. In African countries they get economic rights to extract the resources and diplomatic support, while on the other hand provide them military support.
Improved international relations might be a benefit, but how do you sell that to the mothers of dead Russian soldiers.
Syrian experience proved that you can effectively employ PMCs, local militias and allied foreign soldiers, while having very few own personnel on a ground.
I suspect what Donetsk wants is an elected Kiev that does not shell them.
All the sides agreed and signed Minsk II and it shouldn't be a problem to implement it, provided that there will be a serious intention in Kiev.
Russia has plenty of shipyards that could do with projects to make ships,
The capacities seem to be a bottleneck. All the shipyards and engine producers are filled with orders many years in advance and there are limits to where they can expand. If a company grows too much it gets very hard to manage efficiently. Current submarine, corvette and frigate classes will probably continue production till the end 2020s, while over the same time they'll start producing new projects like Gorshkov M, Husky and UDK. If they decide to make a ship in Ukraine, they know the country and the market and all of its risks better than anybody. Sometimes restoring once good ties can be easier than starting new. I suspect this is on Moscow's long-term agenda.
the US and the EU wont let the Ukraine be friends with Russia or Asia or anyone else
Looking objectively, if Ukraine had to choose, Russia is its perfect integration partner. Besides once large trade turnover, Russians share the same burden of modernizing old Soviet industry. They can connect Nikolayev with their shipbuilders like they've done in Kerch and Feodosiya. The same goes for Antonov. They need orders and Russians capacities.