An official from the U.S. State Department said although Washington stands committed to defending ally South Korea, Seoul must make more efforts to bolster its defense capabilities.

Speaking to Seoul's Yonhap News Agency on Friday, the Department's deputy spokesperson Mignon Houston said Washington will uphold its commitment of "ironclad" security. But she added that the U.S. wants to see Seoul demonstrate the highest level of support and commitment for its defense. 

Houston's comments came in response to a question on whether there will be a renegotiation of a defense cost-sharing deal. The Donald Trump administration has urged allies and partners to increase their defense spending to five percent of their respective gross domestic product(GDP).

Leaders from South Korea and the U.S. have yet to hold a summit since the new administration took office in Seoul. The deputy spokesperson said Washington looks forward to working very closely with the Lee Jae Myung administration and that it is a priority for the Trump administration.

Houston also expressed her cautious optimism over Washington's potential trade deals with Seoul and other partners, adding that the U.S. wants fair agreements that benefit both sides.