For the export of nuclear materials (NM), the NSG guidelines require governmental assurance from the importing State that the NM will be used for peaceful purposes, safeguards and physical protection will be applied, and prior consent will be obtained for retransfer. By providing this assurance, the importing State (recipient) is responsible for fulfilling the obligations required by the exporting States (supplier). If the Nuclear Cooperation Agreement (NCA) has been concluded between the supplier and recipient, it may be replaced by implementing the procedures under the NCA. In the case of NM subject to this obligation, continuous management at the national level is required because prior consent from the supplier may be required for retransfer to a third party under the assurance or may be subject to annual reporting. The obligation swaps are the exchange of obligations of NM without the physical movement of it. Since the physical movement of NM is costly and risky, its obligations are often exchanged for commercial reasons. The basis for obligation swaps is the fungibility and equivalence of NM. The fungibility allows that the inventories of NM need not physically identify the particular NM originally obligated but identify an equivalent quantity of the same isotopic composition. In addition, under the principle of equivalence, even if NM loses its unique physical properties, it can be exchanged by another obligated or nonobligated NM. That is, the principles of equivalence and proportionality allow the comparison of quantities of uranium in different forms. Therefore, it is theoretically possible not only to exchange obligations between NM in same physical form, but also different physical forms of same composition (with the same enrichment), e.g., UO2 powder and its pellets. In U.S., it appears that there are obligation swaps of NM between different enrichment levels, but according to the NCA and its Administrative Arrangement between ROK and U.S., Canada and Australia, the principle of fungibility and equivalence shall not be used to reduce the quality of a quantity of NM. In other words, swaps between NM of different enrichment levels are not allowed under the NCA and AA. However, according to the Supplementary Arrangement between ROK and Canada, the replacement of NM by lower quality NM may only occur where the two States so decide following consultation. The U.S., Canada, and Australia, which are major suppliers of NMs, allow internal obligation swaps within the U.S. and the EU through NCA. The NCA between ROK and these countries does not address whether internal swaps are possible. Since governmental assurance does not impose restrictions on swaps, it can be considered if necessary. Although there is no actual practice of obligation swaps in ROK, research will be necessary regarding the extent to which swaps in ROK should be allowed and the need for government approval or permission.