'has been forceful' is correct and usable in written English.
You can use it when you want to emphasize that a person has taken aggressive action in order to achieve a goal. For example, "The head of the company has been forceful in overhauling the organization's structure."
He has been forceful in demanding that banks buy back dubious loans they sold to Fannie and Freddie during the mortgage mania.
In the days since the plane was shot down, the rhetoric coming from Washington, London and Canberra has been forceful and angry, while the rhetoric coming from The Hague has been careful.
In the past, she often seemed insecure and reticent, letting others speak for her, but she has been forceful and passionate on Gujarat and the importance of protecting India's secular traditions.
The Seven boss, Kerry Stokes, has been forceful in arguing licence fees need to be significantly reduced or abolished, and his company has not been among the media players flying the flag for the government's package.
The response from North Dakota officials has been forceful.
I live in a city whose mayor, Michael Bloomberg, has been forceful and courageous on this issue.
Mr Cohen says such behaviour is alienating China scholars everywhere, many of whom have been forceful advocates of a softer line towards the country.
Mr Obama had been forceful in telling Mr Abe that he needs to confront his domestic lobby groups on trade, in particular the farmers.
His pair of recent albums, "The Hybrid" and "XXX," have been forceful and eccentric, full of improbably catchy songs brimming with off-kilter bravado and sometimes blistering humor.
"There have been plenty of governors who have been forceful, but the question is how do you do it and get results.
