(Reuters) - U.S. President-elect Donald Trump said on Monday a series of tax incentives and tariffs will make U.S. Steel strong again, as he reiterated his opposition to Nippon Steel's planned purchase of the company.

"I am totally against the once great and powerful U.S. Steel being bought by a foreign company, in this case Nippon Steel of Japan," Trump wrote on his social-media platform Truth Social.

"I will block this deal from happening. Buyer Beware!!!"