Gen. Xavier Brunson, commander of U.S. Forces Korea and the Combined Forces Command, drew attention on the 14th when he declined to describe how the CFC's command structure might change after South Korea takes wartime operational control. "The truth is, I don't know right now. And I'm not going to try to speculate," he said at a seminar hosted by a U.S. think tank in Washington.
In October 2018, Seoul and Washington approved a plan for a Future Combined Forces Command at the Security Consultative Meeting and signed guidelines for combined defense after the transfer of wartime operational control, or OPCON. Under that framework, the combined command would operate as an independent standing body, with a four-star South Korean general as commander and a four-star U.S. general as deputy commander. The command was to remain in place even after the OPCON transfer.
Recently, however, voices in the United States have argued that the combined command's role needs to change once OPCON is transferred. Given North Korea's advancing nuclear and missile capabilities and China's efforts to pressure and strike along the entire first island chain, the argument goes, U.S. Forces Korea and U.S. Forces Japan should no longer be kept separate. Instead, a new Northeast Asia combatant command should be created to manage both together.
Critics say the current arrangement, in which the U.S. Pacific Command communicates with U.S. Forces Japan and U.S. Forces Korea through separate channels, is inefficient. A Northeast Asia command, they argue, would allow the U.S. chain of command to retain authority over American troops in South Korea and Japan even after the OPCON transfer, and would ensure those forces could operate across the boundaries of their host countries.
The United States divides the world among 11 combatant commands, seven of them geographic and four functional. One geographic command covers Europe while another covers Northeast Asia. The command responsible for Northeast Asia is U.S. Indo-Pacific Command, with U.S. Forces Korea and U.S. Forces Japan operating separately beneath it.
After the OPCON transfer, the Combined Forces Command is to be replaced by the Future Combined Forces Command, led by a four-star South Korean general with a four-star U.S. general as deputy. Some observers, though, have raised concerns that a four-star U.S. general would resist serving under a four-star South Korean general in the new structure.
Against that backdrop, the repeated calls within the United States for a Northeast Asia combatant command, combined with Brunson's refusal to give a clear answer, have invited a range of interpretations. He said he does not know at this point what the combined command's structure will look like after the transfer, but inside and outside the military there is speculation that the structure will indeed change.
Behind that speculation lies the so-called Pershing Principle — the position, first asserted by U.S. Army Gen. John Joseph Pershing during World War I, that American forces do not serve under foreign commanders. At the time, the U.S. expeditionary force in Europe was smaller than the British and French armies, and the Allied command sought to fold it in as a subordinate unit.
Pershing refused, saying U.S. forces had never served under the command of a foreign army since the nation's founding. That tradition has endured. For that reason, some expect the deputy commander of the Future Combined Forces Command to be a three-star lieutenant general rather than a four-star general. Another projection is that a Northeast Asia combatant command led by a four-star general could be created, with the Future Combined Forces Command placed beneath it.
So has the U.S. military truly never handed command authority to a foreign officer — never submitted to another country's operational control? The answer is that it has. A 2004 report by the U.S. think tank Atlantic Council recorded 17 cases since 1900 in which U.S. troops were placed under the operational control of foreign forces, covering both combat and non-combat missions.
In practice, such cases are not rare. In 1918, in the closing stage of World War I, three U.S. battalions joined Allied forces and served under an Allied general. In World War II, U.S. troops in the Italian campaign took operational orders from the Allied headquarters in Italy, which was led by a British field marshal.
These cases, to be sure, involved small units or short-term arrangements. That makes the agreement by military authorities in Seoul and Washington — placing a South Korean four-star general in command of the Future Combined Forces Command with a U.S. four-star general as his deputy — significant, as it can be read as an exception to the Pershing Principle.
The United States is understood to have agreed to a combined operational plan under which it would send reinforcements to the Korean Peninsula in a contingency, including some 600,000 troops, about 160 vessels including five aircraft carriers, and roughly 2,500 aircraft. Washington would also provide a nuclear umbrella to deter North Korea if necessary, with a South Korean four-star general taking the lead.
At the 50th Security Consultative Meeting in August 2018, the two countries jointly signed the guidelines for combined defense after the OPCON transfer, a document that sketched out the shape of the combined defense posture to come. Changing the combined command's role or command structure from what was agreed in 2018 would require further consultations between the two sides.
One point to watch is that decisions on the combined defense system must pass from the agreement of the two countries' commanders in chief through the Security Consultative Meeting, the Military Committee Meeting and the Future Combined Forces Command. Once OPCON is transferred, what matters is not that a South Korean four-star general will exercise operational command over U.S. troops, but that agreement between the two commanders in chief must come first.
