What are the chances Putin didn't write the article?
He probably had someone to write it down and translate the speech for him. So I have no doubt that Putin was the author of the speech/letter.
Those are mostly stylistic issues but they're indicative of non-native grasp of the English language.
Furthermore it's clearly written by someone with enough capability to express themselves eloquently and succinctly, but as mentioned it's clearly non-native.
Just off the top of my head, Russian doesn't have articles. A Russian learning English is more likely to confuse definite and indefinite articles than a speaker of a Romance language.
I've been learning Thai and teaching English in Thailand. Thai has no articles, no tenses (in the way we think about them) and a simpler syntax with many prepositions and other "small words" omitted. When they start learning English, they often omit too many words and don't conjugate anything, so a sentence like "I don't have any pencils." becomes "No have pencil".