The South China Sea strategic situation probing initiative, based at Peking University, said flights over the region by US surveillance planes had roughly doubled over the past couple of months. In July, the research group said the US carried out 67 reconnaissance missions, compared to 35 in May.
On Chinese social media, the research group noted it appeared the US was “building up a battlefield”.
The SCSPI also suggested the US did not need to conduct surveillance operations so often, because it already had state-of-the-art surveillance equipment.
The group said the US “possesses all-around advanced reconnaissance technology,” so there is “no need” for the nation to make fly-bys so often or so near.
Late last month, the SCSPI said two US aircraft came close to the Chinese mainland, with one coming within around 47 miles of Shanghai.
One of the planes was specialised in submarine warfare, while the other was a reconnaissance aircraft called the EP-3E.
This latter plane is capable of state-of-the-art surveillance, the Federation of American Scientists said.
In a recent interview with Chinese news outlet the Global Times, SCSPI director Hu Bo gave another reason as to why the US may have stepped up its aerial surveillance recently.
He said: “The reason behind the significantly increased US aerial reconnaissance in 2020 could be related to the COVID-19 outbreak.
READ: South China Sea: China orders Trump to ‘stop interfering’ as it warns US ‘escalating’ row
It was the first time China had shown the H-6J bomber, which is able to carry cruise missiles.
Despite tensions in the region, China’s Senior Colonel Ren Guoqiang said drills were a “routine arrangement in the annual schedule,” the Times reports.
Last week, plans for a new Chinese amphibious assault ship were reported.
The unofficially-named ‘Type 76’ ship will be the third-largest ship of its kind.
It will be able to carry up to 30 helicopters plus drones, tanks, smaller boats and personnel.
Some design proposals have been released, showing what appears to be a landing strip.
Analysts have said one particular aspect of a ship – a giant catapult used for launching aircraft – will be the first time technology of its kind is used on an amphibious assault ship.