Japan has decided not to use a military plane to deliver relief supplies to China for victims of the Sichuan quake.
It will instead use a chartered plane to send the materials to the disaster zone, a government spokesman said.
He said that some Chinese officials had been concerned about letting a military plane in - anger lingers in China over Japan's actions in World War II.
Meanwhile, Chinese reports that 1.3m were to be evacuated from near a quake lake turned out to be a false alarm.
Emergency officials later clarified that a drill would take place on Saturday to test evacuation communications procedures, but that no people would actually be moved.
Experts fear an aftershock could burst the fast-rising Tangjiashan lake, which was formed in the 12 May quake when a landslide blocked a river.
Japan has already sent civilian rescue and medical teams to help quake survivors in south-west China.
Ties between the two sides have improved in recent months, but only three years ago there were violent anti-Japanese protests across several Chinese cities.
China has asked for tents and other supplies to be sent to Sichuan
Chinese officials were concerned about a backlash among people who remember Japan's war-time militarism, media reports said.
The plan to fly in a C-130 military aircraft carrying tents and blankets emerged earlier in the week.
Japanese media said it would have been the first flight into Chinese airspace by the Japanese military since hostilities ended more than 60 years ago.
But Mr Machimura said the idea had now been put off.
"As there were concerns in China, Japan and China had discussions and decided to shelve the idea of Self-Defence Forces planes providing transport," he told a news conference.
"This is not an issue that we should risk causing friction."
A commercial aircraft would now be chartered, he said.
Almost 69,000 people died in the quake and another nearly 20,000 are missing, while five million are homeless.