All web sites are vulnerable. In general 50% of internet traffic are human, and 20% are good bots (google, bing, baidu, etc). The last 30% attack, scrape and try to compromise the security systems of any popular site. If you are especially interesting, you will receive more than your share these types of visitors.

Bad bot come from all countries, including the US, China, Netherlands, Russia. They visit daily, usually are not successful but should not be ignored. They are a threat and can be dangerous. The US has their Homeland Security group and their army and navy trolling the internet as well, though they are easier to spot.