Analysts believe the relation between Russia and China is getting more intimate, which might disturb the United States, Russian media reported.

The Russian and the Chinese navies will have their largest-ever joint exercises called “Joint Sea 2015 II” on Aug. 28. The exercises are going to be conducted off the coast of Vladivostok and through the Sea of Japan. The military exercises will be carefully watched by Japan, a major U.S. ally in Asia.

The joint exercises will involve more than 20 ships, Washington Times reported adding that the operations had increased in “size and sophistications” in recent years. There have been five joint exercises held by China and Russia together over the last decade. refers to several experts, who believe that the intimacy between Russia and China was “a marriage of convenience.” Some other experts believe it could indicate “a feature of a new, post-Cold War geopolitical order.”

Russia is supplying modern S-400 surface-to-air missile system to China. According to the Russian news agency, this may “seriously aggravate the American military planning in the Asian-Pacific region.”

The agency added the U.S. would find the Russian-Chinese cooperation “ambiguous.”

“Driving the Russians into the arms of the strategic foolishness of the first order,” quoted international relations theorist John Mearsheimer as saying.

According to the experts, U.S. authorities should give Russia and China some space instead of trying to break the partnership. The U.S. should encourage those powers to have more influence in each other’s backyard, experts said.

Meanwhile, Russian President Vladimir Putin joined a Russian navy team Tuesday, when he visited the Black Sea along the coast of the Crimean Peninsula in a small vessel.