True, but there are a lot of icons, esp. from the late 1700s through to even now that are painted in a western style. If they have been blessed by a Priest then they are icons, but I prefer the traditional Byzantine style.
No matter what country an Icon is painted in( actually its called
writing an icon ), there is only one method used the by the artist to create an Icon. If an Iconographer ignores 2000 years of tradition, and paints in a western style for whatever reason it will never be more than just a painting, whether or not it is blessed by a priest. And while Russia, Greece, Serbia, and even Georgia all have a certain look to the icons done in those countries, they're all done(the real ones anyway) using the same practices and techniques. This involves a large amount of prayers, fasting and concentration. A true Iconographer, after having spent an unspecific amount of time learning all these things(either from a school or an established Iconographer), must then get a blessing from a priest or bishop
before he or she begins to paint. After that they are usually left on they're own unless there is a problem.