Little things can mean a lot, but it isn’t always easy to decipher exactly what those little things mean. Almost on the eve of Chinese President Xi Jinping’s arrival in the United States for an elaborate state visit, something happened over the Yellow Sea, which separates China and the Korean Peninsula. Two Chinese fighter-bombers made what the Pentagon calls “a dangerous interception” with a slow-moving U.S. spy plane on a routine regular patrol.

Apart from the possibility that it could have become a major incident, this appears to confirm earlier speculation that China is trying to take the Yellow Sea out of the sphere of international waters and claim it as Chinese territory. The incident and its implications, whatever they are, has gone almost unnoticed in the Western media. U.S. surveillance of the area is essential to the defense of South Korea, including the defense of 30,000 American troops stationed there.

It could be that the incident was merely coincidental to Mr. Xi’s travel plans. Or it might be that “hawks” in the Chinese military wanted to embarrass the president in Washington as he reaches for more power at home. There’s apparently growing friction between Mr. Xi and the People’s Liberation Army over his aggressive anti-corruption campaign. The campaign has reached high ranks of the military, where the army’s commercial enterprises have been a source of vast corruption.

The president has moved suddenly, say informed Chinese sources, to dramatically cut the size of the People’s Liberation Army. At a ceremony a fortnight ago, commemorating China’s participation in the victory over Japan in World War II, he announced a cut of more than a quarter of a million men from the 2.3 million in uniform. He did not consult with anyone beyond the Central Military Commission which, like the other party and government offices, he tightly controls.

This was long anticipated, along with a reorganization of the army’s old Soviet-style organizational structure. Additional resources were allocated to the air and naval forces. Commentaries in the People’s Liberation Army daily warned that the cuts and reorganization will be difficult to implement. New jobs for the cashiered officers and men will be difficult in an economy with a rapidly diminishing growth rate. One commentator acknowledged the fierce opposition to the cuts.

Military analysts agree the cutback was a part of an overdue modernization, but continued friction will nevertheless test Mr. Xi’s control over the military while it feints toward Japan in the East China Sea and challenges its neighbors in Southeast Asia with a tier of new bases in the South China Sea.