The US has begun the controversial deployment of Osprey military aircraft to the southern Japanese island of Okinawa, amid protests over the move.
The Ospreys arrived at a US base in western Japan in July, ahead of their deployment to Okinawa's Futenma airbase.
Six of the aircraft have now landed in Futenma, reports say.
Okinawa residents have opposed the move, citing safety fears following crashes in Morocco and Florida.
The Osprey is a hybrid military aircraft that has a rotor and can take off like a helicopter but flies like a plane. A total of 12 are to be stationed at Futenma airbase.
They had been due to move on Friday but were delayed by a typhoon.
On Sunday police were called in to move protesters who had tried to seal off the gates to the airbase. Japanese public broadcaster NHK said that a crowd of more than 100 had gathered at the base early on Monday.
Earlier this month, announcing that permission had been given for test-flights, Japanese Defence Minister Satoshi Morimoto said the safety of the aircraft had been confirmed, with the two accidents "caused by human factors".
But opposition to the US military footprint in Okinawa is intense, amid a 15-year stand-off over a base relocation plan.
Okinawa Governor Hirokazu Nakaima said that the concerns of residents about the aircraft should have been addressed before they were moved.
"It is disappointing and extremely regrettable," he said.
Many Okinawan residents want Futenma airbase - which sits in a densely-packed residential area - moved off the island.
The US and Japanese governments have agreed to close Futenma but say they will replace it with a new facility in the less populated north of Okinawa.
Local lawmakers and residents are fighting the plan, saying Okinawa already hosts a disproportionate number of US troops.