Recently Admiral James Lyons (USN-Retired) proposed the return of the U.S. Coast Guard to Taiwan [Strengthening Taiwan’s defenses, The Washington Times]. The 1979 Carter termination of the US-ROC Mutual Defense Treaty left the island out in the cold, but the U.S. Congress replaced it with the Taiwan Relations Act in 1980. In 1996, the Chinese imposed a partial blockade around and over Taiwan with their so-called "missile tests" and the U.S. Navy reacted by sending two U.S. aircraft carriers to patrol the international waters around Taiwan. This partial blockade was an overt act of war by China (see reference here). During the last few years, the South China Sea and Senkaku/Diaoyu Islands have been quietly inundated with Chinese maritime surveillance ships, but these particular Chinese ships are not part of the Chinese PLA Navy (PLAN). Their military role for combatant status is based on naval militias. These maritime militias have been dubbed the "little blue men" of PLAN asymmetric warfare strategies, because they are just tap dancing around an overt act of war (e.g. blockades). American naval assets are seafaring vessels for its military purposes, but the Chinese maritime militia occupy the twilight zone of both civilian and military vessels. Americans, however, have a rough equivalency of the Chinese maritime militia, because the U.S. Coast Guard (USCG) has a dual mission purpose of maritime policing and coastal warfare.
The USCG sailor is subject to the Uniform Code of Military Justice (UCMJ), but the USCG is under the Department of Homeland Security during peacetime. The USCG, however, is transferred to the Department of the Navy during wartime. The Coasties (USCG) are a U.S. maritime police force on the high seas, and the continuous presence patrols by the USCG is directly beneficial to the Taiwan maritime enforcement of their Taiwan fishery agreements. Admiral Lyons has suggested returning an American presence to Taiwan and surrounding waters for fishery patrols with the Taiwan coast guard. The USCG presence would send a clear message to the PLAN and their "little blue men" about Beijing’s creeping expropriation of claimed areas around Taiwan. Whether the Coasties would ever visit Taiping Island is another matter for debate, but the Penghu Islands are too vulnerable to "salami slicing" or "claim jumping" by the PLAN. Sooner or later the Chinese invaders will attempt to take control of these nearby outer islands and then blockade the bigger island of Taiwan. This would be boots on the ground by Chinese nationals, and they would exercise actual control of the invaded areas.
The Taiwan Relations Act provides for the provision of defense articles and services by the United States, but the sound defense policy basis for the Coasties would be the Truman Statement of 1950. This enduring statement established a corollary policy for the 7th Fleet containment of the Chiang Kai-shek. This action was a kind of naval blockade of the ROC on Taiwan. Recently, the PLAN has attempted to establish their own version of no-fly zones and exclusive maritime areas around the seafaring peripheries of Taiwan. This PLAN strategy is like a game of Chinese chess (weiqi or go for Learning from the Stones) and each artificial island is another stepping stone towards the encirclement of Taiwan and Penghu. The PRC has also recently announced the creation of special maritime courts for the South China Sea and its artificial island claims (Taipei Times). The USCG patrols would put Beijing on notice, and the USCG would exclude the Chinese maritime militia from any claimed exclusive fishing areas around Taiwan. The USCG enforces the long arm of maritime law with the Maritime Drug Law Enforcement Act (MDLEA), and the MDLEA offers itself as a very unique tool of American naval lawfare against the PLA maritime militia. This U.S. law has been highly effective around Central American countries, and the U.S. law allows for supplemental agreements for USCG customs enforcement on behalf of the host nation. The USCG has its own maritime police jurisdiction to intercept foreign vessels on the high seas, and the MDLEA provides for American federal court jurisdiction beyond the 12 nautical mile territorial limits around Taiwan and Penghu Islands. This anti-smuggling mission allows for USCG maritime policing of international interdiction activities (e.g. Taiwan fishery agreements), because there is a nexus of Taiwan and Penghu areas for the US federal court purposes of the Taiwan Relations Act. Here, the Fifth Amendment Due Process clause should recognize the USCG nexus of activity between the U.S. Customs Area and WTO autonomous separate customs territory of Taiwan and Penghu Island. This American nexus was established by the Truman Statement of 1950, and its corollary policy for Taiwan and Penghu allowed for the 7th Fleet to patrol the Taiwan Straits during the Korean War in 1950-53. In other words, there is sufficient international legal authority for a USCG "virtual blockade" of the Taiwan Straits without triggering a full-blown blockade with China (e.g. 1861 military practices of coastal blockades include partial military blockades with maritime interdictions on the high seas. The 9th Circuit is more particular about the nexus requirement, and this federal circuit for the Western Pacific would exercise a quasi-personal jurisdiction over patrolled maritime areas in the fishing zones around the island of Taiwan. (MDLEA Nexus) The international law of the sea works in conjunction the domestic law of MDLEA. The USCG can stop and search any foreign vessel on the high seas including stateless ships. The USCG patrols are just maritime police activities, and U.S. anti-smuggling operations are really required to exclude the PLAN naval militia from creeping expropriations of Taiwan fishing areas. Therefore, the high seas jurisdictional nexus of U.S. maritime activities is well-established for American law enforcement by USCG drug-smuggling and potential customs interdictions of the PLAN naval militia vessels in the Western Pacific.
Before the U.S. maritime patrols proposed by Admiral Lyons could begin, the USCG needs to establish an Acquisition & Cross Servicing Agreement (ACSA) with Taiwan. The USCG visits to various ports in Taiwan is logistically necessary for resupplying and refueling. For contingency and training missions, ACSA provides for the logistics support, services, and supplies (e.g. base support and logistical activities) by the Taiwan governing authorities. The related federal law allows for "acquisition only authority" from the Taiwanese logistics suppliers, but future joint-operations with the Taiwan coast guard requires a bilateral agreement for mutual support by American visitors from Taiwanese sources. In this era of tight defense budgets, there is included authorization for the bartering of these services and supplies, too. The ACSA process is a fast-track channel for securing this bilateral agreement between the USCG and Taiwan, and USCG negotiation requires minimal supervisory approval from the U.S. State Department. Because this is an executive agreement, there are no treaty formalities of Senate ratifications. ACSA provides for mission conduct of contingency operations by visiting forces, and the U.S. Department of Defense has statutory authority for the negotiations of ACSA under the Undersecretary of Defense for Acquisitions, Technology, and Logistics USD(ALT). The USCG is the requiring activity, and the proper military authorities only need to initiate the process for a typical completion of negotiations within a six-month period. The ACSA logistics conduit, however, does not allow for any bypassing of the Foreign Military Sales (FMS) for major weapons systems. The potential maritime presence of the USCG requires the full cooperation of the Taiwan governing authorities, and the ACSA negotiation and signing process allows for the rapid return of American naval assets to the Taiwan and Penghu Islands.