Copernicus
Industrial Grade Linguist
...But Boeing and Seattle? Are they safe? Oh, right. Phew. Yes.
I worked there for a quarter of a century, so I know the company fairly well. Boeing is spread all over the country, but Seattle mostly a site devoted to commercial manufacturing. Space and military are located more in California, St. Louis, and Alabama. The headquarters is Chicago. Trump, of course, would be ignorant of such things, so he might genuinely have thought that Russian spies were stealing military secrets in Seattle.
The main problem, as far as security goes, has little to do with physical location. It has to do with penetration of the internal computer systems, which were probably thoroughly compromised many years ago. Boeing went through a period where it did a great deal of business in Russia (and still does with China). It hired Russian engineers and had important facilities in Russia. As the US and Russia grew apart, the company had to divest itself of that strategy, although it remains very heavily invested in China. Russian and Chinese engineers were very good, cheap labor for the company.
I have no doubt that Russia and China can penetrate any system in the company, although the security is now much better than it used to be. When I worked there, there were frequent phishing attempts sent to me, which I reported. However, they were doubtless successful in a company with so many people, all of them with accounts on the network. Worse yet, China is one of Boeing's main customers, so that country is probably a much larger threat to security than Russia. I would be very surprised if there were no employees within the company who were stealing data and strategic plans and passing them along to foreign governments.