CNN news 2017-05-25 Moving to the Korean Peninsula, where officials are examining satellite images of a potential volleyball game. It's a popular sport in the communist nation of North Korea, and according to 38 North, a service that monitors the secretive country, these pictures appear to show volleyball games taking place at a North Korean nuclear test site. People who work there might be having some down time. They might be standing by for orders from their nation's leader, Kim Jong-un. The U.S. military says North Korea is able to carry out a nuclear weapons test at anytime and it's not likely to announce it first. Its neighbor to the north, China, is reportedly making preparations for trouble in North Korea. A U.S. defense official says Chinese bombers were put on high alert this week and that an extraordinary number of Chinese warplanes are being prepped for possible service. Why is China concerned? For one thing, it's North Korea's closest ally. North Korea depends on China for 80 percent of its international trade. For another, if war breaks out on the Korean Peninsula and the North Korean government collapses, refugees may try to flood over the country's border with China. It also doesn't like the possibility of a reunified Korea under a South Korean government. South Korea is an ally of the U.S. PAULA HANCOCKS, cnn INTERNATIONAL CORRESPONDENT: This is Max Thunder, a massive air exercise between the U.S. and South Korea. There is about 80 aircraft involved in this, more than 1,500 personnel. Now, we're told it's routine: It is annual. The lieutenant colonel in charge of it said that it has been planned for months, and they don't have a specific enemy in mind when they're carrying out this exercise. But, of course, with what is happening on the Korean Peninsula, and that right now, means that this is very much in the spotlight. We know that North Korea has blamed the United States for pushing to almost the brink of war. And there is rhetoric on both sides being very strong at this point. But from this point of view, the people who are involved in this particular exercise say that it's just important for them to be able to know how to work with each other in case of a war. We're being told that this is as close a simulation as you can get to a possible war situation. Now, of course, North Korea does not like these military options. They see this as a practice for invading North Korea. The U.S., though, says that they are defensive. China doesn't like them either. They have even suggested to the U.S. and South Korea that if they actually halt these drills, then North Korea may suspend their nuclear and missile program. It's not a new suggestion, and it's not a suggestion that the United States accepts. Paula Hancock, cnn, at Kunsan Air Base in South Korea.