It is a two-hour flight from Japan's southern islands to an arena where tensions are high and so are the stakes. A US aircraft carrier in Asian waters, a window into America's role in some of the world's most contested seas. Jets are always ready here. They can launch as many as three every 50 seconds. They're flying in international skies over international waters.

But.

Some, like the Taiwan Strait and the South China Sea, are areas that China claim as its own. If tensions between these superpowers ever spill over, it will happen here, and these crews will be the front line. China's military is increasingly assertive in these regions. In the tower where they manage the launches and landings, a hint of how often they have to react.

We can get our aircraft in the air very, very quickly. I mean, a matter of minutes, we can get them. You've done that recently? The scramble recently? Yeah, we've put aircraft in the air very, very quickly.

But most alarming is this, US video of Chinese jets flying dangerously close, in this case, just 10 feet away. The risk of accident high, the US message direct.

It is dangerous and unprofessional, but that's not the way American mariners and American air pilots fly. We are focused on what our mission is, building up our strengthening and deepening deterrence.

It's against this precarious backdrop that the presidents will meet here in San Francisco. Diplomacy redoubled. Since they last met, relations had plummeted disagreements from Taiwan to tax sanctions from Ukraine to this, the so-called spy balloon saga. Bang, Bang, Bang, Bang, Bang. That's my Air Force right there, buddy. But both sides are now making an effort. Just listen to the Chinese government holding back from its usual critiques. Amidst all those differences, will this meeting meaningfully move the dial between your countries.

The two presidents will have in-depth communication on issues of strategic, overarching, and fundamental importance in shaping China-US relations and major issues concerning world peace and development. I think it will be an important meeting.

Meaningful breakthrough is still highly unlikely, and back out at sea, it's not hard to see why. China views drills like this between the US and Japan as highly provocative, aggression in its backyard. Nonetheless, there is a shared desire for stabilization. Both quietly fear the alternative. But for all the warm gestures when you're here, there's a sense of how easily it could all be blasted off course. Helen Anne Smith, Skynews in Beijing.