So, you know how sometimes you don't like someone in school or daycare, and there's maybe a little bit of a fight or an argument? Well, countries can be like that too. In this case, Russia and the United States are two countries that have had some fights and arguments in the past.
It all started a long time ago, during something called the Cold War. The United States and the Soviet Union (which included Russia) were in a big disagreement about a lot of things, and it led to a lot of tension between the two countries.
Eventually, the Cold War ended, but some of that tension still exists today. The United States and Russia often disagree on things like how to deal with other countries, and sometimes they get into arguments or even do things that hurt each other.
But sometimes they get along okay too. They might work together on something that's important to both of them, like fighting terrorism or protecting the environment.
Overall, the relationship between Russia and the United States is complicated, a little bit like a huge puzzle that's always changing. But there's really no reason that the two countries can't eventually figure things out and get along better.