The basic idea is that "verstärken" implies "strengthening something that is already strong", while "stärken" only refers to "to strengthen" (which can be pretty close admittedly). Accordingly, you can often use both, but not always. Especially when you are refering to things that already contain the notion of "strong" (defenses/storm/effect on something/.....), you would prefer "verstärken" (which can also be used reflexively)
The Language Level symbol shows a user's proficiency in the languages they're interested in. Setting your Language Level helps other users provide you with answers that aren't too complex or too simple.
Has difficulty understanding even short answers in this language.
Can ask simple questions and can understand simple answers.
Can ask all types of general questions and can understand longer answers.
Can understand long, complex answers.
This answer was given within 60 minutes of the question being posted.
How do you say "Hello" in Korean? Find out on HiNative!