Nations Command launched senior-level talks last month to narrow differences over the command's role after Seoul takes back the wartime operational command of its forces from Washington, government sources said Tuesday.

The allies have shown differences over the UNC's future authority and roles amid speculation that the US could be trying to expand and strengthen the UNC in an attempt to keep control of the South Korea-US Combined Forces Command even after the OPCON transfer.

After the transfer, a South Korean general is supposed to command the CFC, with a US general playing supportive roles, which is bound to shrink the US' control over South Korean troops in contingencies. Currently, a four-star US Army general helms the CFC.

The US has been trying to strengthen the UNC under what is dubbed a "revitalization campaign" since 2014.

According to the sources, the senior-level consultative body was set up last month to discuss such sensitive issues on a regular basis, with South Korea being represented by its deputy minister for national defense policy and the UNC by its deputy commander. 

Also involved are officials from Seoul's defense ministry and US Forces Korea, they added.

"There are many things to talk about over its role and the commander's authority in the run-up to the envisioned OPCON transfer," a source said, acknowledging differences in key issues regarding the UNC's potential expansion.

As part of the revitalization plan, the UNC beefed up its staff and had senior officials dedicated exclusively to their UNC roles rather than taking multiple responsibilities in other entities.

Over the course, the US allegedly has sought to include Japan as an official UNC member, an idea flatly rejected by Seoul that says Tokyo is not entitled to such status, in accordance with UN Security Council resolutions. 

Washington has also reportedly maintained that the UNC should be allowed to give directions to South Korea's Joint Chiefs of Staff in contingencies in order to fulfill its primary role of maintaining the armistice on the Korean Peninsula. 

But South Korea was negative on the idea, as that could infringe on South Korea's authority, and those instructions could collide with the JCS' military operations.

"Discussions regarding the matter need to be and will be done by comprising more government entities from South Korea and the US," another source said. 

Established in 1950 under a UN mandate in response to North Korea's military provocations, the UNC has played a role as the enforcer of the armistice agreement that halted the 1950-53 Korean War. It is currently led by US Gen. Robert Abrams. (Yonhap)