An expert from the U.S. think tank Center for Strategic and International Studies(CSIS) says President Donald Trump will likely demand a hike in Seoul's defense cost-sharing during his upcoming summit with President Lee Jae Myung.

In a report published on the think tank's website on Friday, CSIS Korea Chair Victor Cha said Trump invited Lee to the White House within the next two weeks as a “reward” for the recent trade agreement, which includes Seoul’s pledge to invest 350 billion U.S. dollars in exchange for the U.S. lowering its reciprocal tariff rate to 15 percent.

Cha said Trump is expected to use the summit not only to celebrate the trade deal, but as leverage on South Korea for more concessions on investment, non-tariff barriers, and currency manipulation.

He added that the two leaders could discuss other related issues beyond trade, such as a new defense cost-sharing deal, where Washington would ask for a significant increase in Seoul’s annual contribution, currently around one billion dollars.

As for the announced trade deal itself, Cha said many details remain unclear, particularly those involving South Korea’s additional market openings in rice and beef, as well as its participation in the U.S. liquefied natural gas(LNG) project.