U.S. Republican presidential nominee Donald Trump denounced the free trade pact with South Korea as a "job killing" deal Thursday, pledging to totally renegotiate what he called "horrible" trade agreements.

It was not the first time Trump has voiced criticism of the Korea-U.S. trade agreement, but Thursday's remark carried greater weight as it came in his first speech since formally winning the nomination at the national convention under way in Cleveland.

In a nationally televised nomination acceptance speech, Trump criticized his Democratic rival Hillary Clinton for supporting many trade deals hurting the American middle class, including the North American Free Trade Agreement, and for supporting China's entrance into the World Trade Organization.

"She supported the job-killing trade deal with South Korea. She has supported the Trans-Pacific Partnership. The TPP will not only destroy our manufacturing, but it will make America subject to the rulings of foreign governments," Trump said.

Trump said he will never sign any trade agreement that "hurts our workers, or that diminishes our freedom and independence. We will never ever sign bad trade deals. America first again! America first!" Instead, he said he will make individual deals with individual countries.

"No longer will we enter into these massive deals with many countries that are thousands of pages long and which no one from our country even reads or understands. We are going to enforce all trade violations against any country that cheats," Trump said.

That includes stopping China's "outrageous theft of intellectual property, along with their illegal product dumping, and their devastating currency manipulation," he said.

"Our horrible trade agreements with China and many others will be totally renegotiated. That includes renegotiating NAFTA to get a much better deal for America and we'll walk away if we don't get that kind of a deal. We are going to start building and making things again," he said.

Trump made no direct mention of renegotiating the trade deal with Korea specifically, but is widely expected to do so if elected to the White House. His aides have said that Trump wants to go back to "ground zero" with regards to the trade deal with Seoul.

Trump also reiterated his determination to force allies to pay more for an American troop presence.

"We will completely rebuild our depleted military, and the countries that we protect, at a massive loss, will be asked to pay their fair share," he said.

In an interview with the New York Times published earlier in the day, Trump made a similar remark that he is "absolutely prepared" to tell U.S. allies, "Congratulations, you will be defending yourself," unless they agree to shoulder more of the cost of an American troop presence.

Making allies pay up for an American troop presence has been one of the top foreign policy priorities for Trump. The real-estate businessman has argued that it makes no sense for the U.S. to help defend such wealthy allies as Japan, South Korea and Saudi Arabia in exchange for little. He also says the U.S. can no longer afford to be the policemen of the world.  (Yonhap)