今年上半年以來，美國逐步將海岸警衛隊部署到南海。此舉可能意味着中美在南海的“灰色地帶”較量將成為常態。

早在2016年，美國國內就開始討論將海警部署到南海，以應對中國的所謂“灰色地帶”，即海上民兵和海警。近三年來，隨着中美關係惡化和兩國南海較量持續升級，這種討論日益得到美國朝野的支持。今年3月美國海警“伯索夫”號巡邏艦穿越台灣海峽，5月美菲海警在黃岩島附近海域開展七年來首次聯合訓練。6月底，美國海警太平洋地區司令費根明確表示，已在日本橫須賀基地部署“伯索夫”號和“斯特拉頓”號兩艘國家安全艦，用以加強南海沿岸國的漁業執法領域能力建設和幫助其海上“維權”，監視中國海上民兵武裝，配合美軍南海行動。至此美國將海警部署到南海的決策一步步明朗。值得注意的是，美國海警從缺少預算到正式進入南海，顯然已經得到國會、五角大樓和白宮的支持。種種跡象都表明，美國海警部署到南海將逐漸常態化。

國際社會普遍認為，部署海警是美國再次升級南海軍事行動的舉措。但事實恐怕不僅於此，此舉還預示着美國正在調整其南海政策。

一是政策方式正在由以硬實力、硬對抗為主，轉變為軟硬兼施、軟力量和軟對抗佔主要地位。過去的兩年里，美國南海政策的主線是以航行自由行動壓制中國。美軍艦機在南海穿（飛）越本質上是一種武力展示，其背後邏輯是“強權即公理”的硬實力對抗。相較而言，海警作為執法力量，雖被稱為“準軍事力量”，但實質仍是一種“軟力量”。換言之，雙方海警南海較量的重點將由“誰的力量更強”，轉變為“誰能說服國際社會相信自身的法理主張更合理”。當然，美國並不會放棄以海空力量作為威懾的政策選擇，但這種方式將逐漸成為背後的威懾力量。

二是美軍在南海的政策目的正從過往的以遏止中國力量擴張、保持地區力量分佈中的壓倒性優勢為主，轉向既要維持力量壓倒性優勢，又要確保在南海地區的長期穩定存在。相較於強大的海空軍，海警的力量顯然稍遜一籌，但其部署和行動預算開支及政治外交風險相對較低。此一點既符合特朗普上台以來降低全球霸權成本的計劃，有助於美軍實現在南海的長期穩定存在，也可以維持美國在南海地區與中國的“軍事平衡”。

三是政策實踐逐步由單邊主義向雙邊和多邊主義轉變。2010年以後，美國前後兩屆政府都一直尋求以多邊和雙邊主義遏制中國在南海的“擴張”行動。特別是特朗普上台以來，一直在推動菲律賓、澳大利亞、日本、韓國、英國等域內域外盟友參與南海聯合航行自由行動。但出於各自的戰略考量和利益訴求，各方並未參與美方行動，而是採取“迂迴策略”，通過自主的單邊海上行動予以配合和支持。但美國以海警作為合作對象，降低了聯合行動的敏感性，大大消除了其盟友和夥伴國的顧慮，也提高了聯合行動倡議的可操作性。目前，美國不僅已與菲律賓建立海警合作關係，還與越南開展海警部門間的交流，如向越南提供24艘海警船、海警部門間訪問等。藉助海警部門間的聯合訓練、力量建設、維護航道安全和環境保護等領域的合作，以執法和維護公海自由的名義，美國有望實現與區域內外國家間的雙邊和多邊聯合行動。

伴隨美國海警在南海的常態化存在，中美之間圍繞海警的“準軍事”較量無疑將日趨頻繁，而兩國在南海全面競爭和對抗的態勢也將繼續惡化。

其一，隨着美國常態化、強化在南海的海警力量部署，美國海警與中國海警和海上漁民（船）的糾纏勢必增加。目前美方已經明確，它在橫須賀基地兩艘船的主要目的之一就是監視中國海上民兵。因而，中國海警在南海斷續內海域，尤其在仁愛礁、黃岩島、鐵線礁、瓊台礁等島礁附近海域的巡航執法行動，以及漁民船隻在南海傳統漁場的捕魚活動，都將遭到來自美國海警船的干擾。需要警惕的是，中美海警尚缺乏類似海軍部門之間的海上相遇規則，一旦相遇還將面臨如何保持自我約束、規範行動、有效溝通等一系列難題，發生誤判和不測事件的可能性較大。其二，隨着美國海警以執法名義進入南海，中美在南海的法理較量將逐步加劇。特別是美國認為中國應該遵守菲律賓南海仲裁案裁決，但中國奉行“不接受、不參與、不承認”的政策。未來，兩國海警在南海行動的矛盾首先將是“誰的行動和存在更具有法理依據”，雙方南海法理較量將逐步凸顯並日陷焦灼。其三，美國利用海警編織的合作網絡與中國在南海的競爭將加劇。就目前而言，菲、越、日、澳等域內外國家都傾向於支持仲裁裁決和美軍在南海的行動。美國將利用海警合作構建一個以中國為反制對象的聯盟和夥伴國網絡，中美南海互動將愈加陷入帶有冷戰色彩的對抗之中。

Since the first half of this year, the United States has gradually deployed its Coast Guard to the South China Sea, portending the normalization of the gray area contest between China and the United States.

In 2016, the United States discussed the deployment of its Coast Guard to the South China Sea to deal with China's gray areas, namely the maritime militia and coast guard. In the past three years, with the deterioration of China-U.S. relations and greater competition between the two countries in the South China Sea, this move has gained support. In March, the U.S. Coast Guard Cutter Bertholf sailed through the Taiwan Strait. In May, U.S. and Philippine coast guard forces held an exercise in the waters near Huangyan Island for the first time in seven years. Then, in late June, U.S. Coast Guard Pacific Area Commander Linda Fagan said that Coast Guard Cutters Bertholf and Stratton had been deployed in conjunction with other U.S. military vessels in Japan's Yokosuka Naval Base to help law enforcement in the South China Sea and capacity-building in the fisheries enforcement realm, as well as to monitor China's maritime militia. All this lays bare the U.S.'s intention to deploy its Coast Guard to the South China Sea. It is worth noting that the U.S. Coast Guard has received financial support from Congress to the Pentagon and the White House to enter the South China Sea. These are indications that the deployment of the U.S. Coast Guard to the South China Sea will become the norm.

The international community generally believes that the deployment of the U.S. Coast Guard is meant to upgrade U.S. military operations in the South China Sea. It may also indicate an adjustment to the U.S.'s South China Sea policy.

First, the U.S. is shifting from an approach that uses hard power and confrontation to one that uses soft power plus select hard measures, as well as some purely soft power and confrontation. In the past two years, its main policy line has been to suppress China's freedom of navigation. The use of American warships and aircrafts in the South China Sea is a kind of force display, the logic being that might is right. In comparison, the coast guard, as law enforcement, is a paramilitary force, but it still is essentially soft power. In other words, the focus of the contest between the two sides in the South China Sea will shift from who is stronger to whose legal principles are more reasonable to the international community. Of course, the United States will not abandon its use of sea and air power as deterrents, but this approach will be a deterrence from behind.

Second, the policy objectives of the U.S. military in the South China Sea are shifting from curbing China's power expansion and maintaining the U.S.'s regional power advantage to maintaining its overwhelming advantages in force and ensuring its long-term stable presence in the South China Sea. Compared with U.S. naval and air forces, the U.S. Coast Guard is obviously inferior, but its deployment and operational expenses and diplomatic risks are relatively low. This is in line with President Trump's plan to slash global hegemonic costs while still helping the U.S. military achieve a long-term stable presence in the South China Sea and maintaining the U.S. military balance with China in the region.

Third, the country's policy has gradually transitioned from unilateralism to multilateralism. After 2010, both Obama's and Trump's administrations have sought to contain China's expansion in the South China Sea with multilateral and bilateral tools. Since Trump took office, he has encouraged allies such as the Philippines, Australia, Japan, South Korea, and the United Kingdom to participate in joint freedom of navigation exercises in the South China Sea. However, due to their respective strategic considerations and interests, the countries instead adopted a roundabout strategy to work with the United States through independent unilateral maritime actions. However, the United States has successfully used cooperation between coast guards to reduce the sensitivity of joint operations, eliminating a great concern of its allies and partner countries. At present, the United States has not only established a cooperative coast guard relationship with the Philippines, but it has also conducted exchanges with the Coast Guard in Vietnam. The United States provided Vietnam with 24 coast guard vessels and enabled exchange visits. Through joint training, strength building, maintenance of waterway safety, and environmental protection between Coast Guards, the United States can be expected to achieve joint operations with countries within and outside of the region in the name of law enforcement and the maintenance of freedom of the high seas.

Along with the normal presence of the U.S. Coast Guard in the South China Sea, the paramilitary contest between China and the United States around coast guards is likely to continue, possibly deteriorating into full competition and confrontation.

With the strong and regular deployment of the U.S. Coast Guard in the South China Sea, the entanglement between the coast guards and fishing boats at sea is bound to increase. At present, the United States has clearly stated that the primary purpose of the two ships at the Yokosuka base is to monitor China's maritime militia. Therefore, the U.S. Coast Guard may interfere in the China Coast Guard's cruise enforcement activities in the inner waters of the South China Sea, especially in the waters near Ren'ai Reef, Huangyan Island, Tiexian Reef, and Qiongtai Reef, as well as China's traditional fishing activities in the area. It should also be noted that the two countries' coast guards still lack rules for maritime encounters like those that have been established for encounters between the navies. Once they meet, they will face difficulties in how to maintain proper identification, self-discipline, standardized actions, and effective communication.In addition, with the U.S. Coast Guard entering the South China Sea in the name of law enforcement, the legal contest between China and the United States in the South China Sea will gradually increase. In particular, the United States believes that China should abide by the South China Sea arbitration with the Philippines, but China does not accept, participate in, or recognize it. In the future, the conflict between the U.S.'s and China's coast guards in the South China Sea will be based on which side has greater legitimate legal basis for its actions and presence.Finally, the competition between the network of regional coast guards will intensify. For now, countries inside and outside the region such as the Philippines, Vietnam, Japan, and Australia, tend to support the arbitral award and the U.S. military's actions in the South China Sea. The United States will continue use coast guard cooperation to build a network of alliances and partner countries that target China, meaning that China-U.S. interactions in the South China Sea will increasingly resemble a Cold War-style confrontation.