A new nuclear accord concluded between South Korea and the U.S. on Wednesday was described by the two sides as striking a balance between Seoul’s need for nuclear autonomy and Washington’s will to keep its global nonproliferation campaign uncompromised.

A South Korean Foreign Ministry official called it a win-win deal based on mutual trust between Seoul and Washington. U.S. Ambassador to South Korea Mark Lippert said in a statement that the deal marked a “significant achievement” for both sides.

The new agreement, which was reached after four and a half years of negotiations, gives South Korea more leeway in making preparations for reprocessing spent fuel and enriching uranium.

South Korean scientists will be allowed to conduct some early-stage research into a new type of technology to reprocess spent fuel, called pyroprocessing, which is said to have less chance of being used for building nuclear weapons. The accord has also opened the door for Seoul to produce low-enriched uranium.

Instead, South Korea stated its commitment to the global nonproliferation regime.

Under the deal that replaces the existing pact signed in 1973, South Korea will also be permitted to transfer nuclear equipment and other related materials from the U.S. to a third country under a comprehensive endorsement. So far, it has been required to secure prior approval from the U.S. for the outbound shipment of each and every nuclear part or technology. This measure is expected to help boost South Korea’s exports of nuclear reactors by dispersing concerns of potential buyers over the possibility of delays in projects due to U.S. opposition.

The accord still falls short of the expectations of some South Korean experts who took note of the Washington-Tokyo nuclear deal signed in 1988, which allows Japan to reprocess spent fuel and enrich uranium virtually on an unlimited basis.

Certainly, the U.S. dropped the “gold standard,” which requires partner countries to forswear enrichment and reprocessing, in its new accord with Seoul. But the two sides left substantial discussion on the sensitive part of broadening South Korea’s nuclear autonomy to a high-level consultation channel to be set up later.

The new agreement, which will remain in force for 20 years, calls for bilateral cooperation based on the “principles of equality and reciprocity.” This spirit is to be fully promoted in opening an era of full-scale nuclear cooperation between the two allies.