The U.S. State Department said Wednesday that the Korea-U.S. free trade pact is an agreement that would serve the interests of both nations.

The remarks came a day after the liberal parties led by the opposition Democratic United Party conveyed a letter to the Washington government in which they threatened to scrap it should the U.S. reject their demands for renegotiations over disputed clauses.

In an e-mail reply to the Yonhap news agency, the department stressed that the pact would serve as a historic opportunity to strengthen the bilateral strategic alliance, a key partnership in the Asia Pacific region.

The liberal forces argue that without revisions the pact could encroach upon Korea’s economic sovereignty, while stressing that the ruling bloc railroaded its ratification through parliament last November.

The pact is expected to take effect later this month or early next month.

The Korea-U.S. FTA was signed in 2007 under the previous liberal rule of President Roh Moo-hyun and his Uri Party, the DUP’s precursor. The incumbent conservative Lee Myung-bak administration led a renegotiation of the deal in 2010 at the request of the U.S.

By Song Sang-ho (sshluck@heraldcorp.com)