South Korea's top presidential aide says the country cannot invest 350 billion dollars in the United States in cash, as suggested by U.S. President Donald Trump.

National Security Adviser Wi Sung-lac made the remarks Saturday during a local television interview, addressing questions about whether trade negotiations with the United States have grown more complex following President Trump's recent assertion that South Korea's pledged 350 billion dollar investment would be paid up front.

Seoul agreed to provide the investment package as part of an initial deal with Washington in exchange for a reduction in U.S. tariffs on South Korean imports. 

However, the two sides have yet to finalize how the package will be structured and implemented.

Wi emphasized that the issue is not a matter of negotiation tactics, but rather that the proposed amount is objectively and realistically beyond what South Korea can afford.

He added that, regardless of political affiliation, it is difficult to dispute that reality, and discussions on alternative arrangements are currently underway.

Wi also noted that one of the target timelines for concluding the negotiations is the Asia-Pacific Economic Cooperation (APEC) summit, set to be held in Gyeongju in October.