China’s increasingly truculent behavior in the East and South China Seas has generated apprehension over China’s intentions and deepened U.S. concerns, especially over freedom of navigation, land reclamation and the potential militarization of disputed features by China. Analysis has focused primarily on the law of the sea, the legitimacy of China’s expansive claims that are now being challenged by the Philippines in the Permanent Court of Arbitration (with a long-awaited decision expected on July 12), and much debate over U.S. policy and ASEAN’s response. However, little analysis has been devoted to the alliance security dilemma and how this influences the behavior of U.S. allies, Japan and the Philippines, in their disputes with China over the Senkaku Islands and the South China Sea respectively.

While Washington takes no position on the sovereignty issue, the dynamics of the security dilemma in alliance politics influences the behavior of U.S. allies and China. In fact, there are two games—the alliance game and the adversary game. Forming alliances incurs costs by taking on commitments to defend allies which reduces Washington’s freedom of action and can entangle the U.S. in disputes with its allies’ adversary, in this case China. Specifically, the alliance security dilemma is how resolutely the U.S. should commit to support its allies. A strong commitment can result in entrapment in an unwanted dispute (with China in this case). If U.S. allies feel assured that the Washington is strongly committed to the alliance they may become more intransigent in their territorial disputes with China or engage in risky behavior that could lead to a militarized dispute. Conversely, a week commitment by the United States will increase its allies concerns over U.S. support, but can restrain their risky behavior and encourage them to seek a compromise resolution of their disputes with China, thus reducing U.S. concerns over entrapment.

In the case of the alliance adversary, the obverse is true. If Beijing perceives a weak commitment on the part of the U.S. to its allies, China may show little willingness to engage in negotiations to reach a compromise settlement or possibly engage in more aggressive behavior risking war. However, if China perceives that the U.S. doggedly supports its allies, this may lead to less intransigent behavior on the part of Beijing.

The upshot is any move in the alliance game affects the adversary game and vice versa. The sum of these effects must be considered within the larger strategic calculations. An expansionist adversary can be deterred by showing firmer commitment to one’s ally. However, strong alliance commitments risk entrapment and can encourage an ally’s risky behavior. But a weak commitment increases strains within the alliances and raises questions about the extent allies can count on U.S. backing in case of confrontation. But this hopefully motivates allies to pursue negotiations and a peaceful resolution of these disputes. A strong U.S. commitment to allies incurs side-effects by increasing tensions in U.S.–China relations, but this can deter China from engaging in more aggressive behavior and open the way for compromise. Therefore, the alliance security dilemma requires careful consideration of the trade-offs between the alliance game and the adversary game.

In the case of Japan, the U.S. does take a clear stand regarding obligations to help Japan defend territory over which is exercises administrative control, but in the case of the Philippines the U.S. is much more circumspect. A central question is whether or not the US-Japan mutual security treaty applies in the case of a militarized conflict over the Senkaku/Diaoyu Islands. At the time of the Okinawa reversion in 1972, the U.S.-administered Senkaku Islands were included. At the time, the United States stated that disputed sovereignty is a matter between Japan and China, and the United States maintains neutrality; the United States was simply transferring administration over the islands to Japan, not recognizing Japanese sovereignty. This left the question of the U.S. obligation to help defend the islands vague.

Secretary of State Clinton clarified the U.S. position on October 2010. Responding to a journalist’s question Clinton stated: “Well, first let me say clearly again that the Senkakus fall within the scope of Article 5 of the 1960 U.S.-Japan Treaty of Mutual Cooperation and Security. This is part of the larger commitment that the United States has made to Japan’s security.” While government officials have stated on many occasions that the U.S. expects the claimants to resolve disputes through peaceful means, among themselves, Richard Armitage, the former Deputy Secretary of State, said that Beijing misunderstood this U.S. position of neutrality over the sovereignty issues and he made clear “that the U.S. is not neutral when one of its allies is being coerced, intimidated, or the victim of aggression,” stressing that the U.S.-Japan Security Treaty “implies that the U.S. has a responsibility for defending the Senkakus, and that hardly makes the country neutral.” Washington has taken steps to back up its commitment to help Japan defend the Senkaku Islands.

During his visit to Washington, DC in January 2013, Foreign Minister Fumio Kishida expressed appreciation for U.S. support: “I conveyed to Secretary Clinton that Japan very much values the commitment shown by the United States over the Senkaku Islands based on the Japan-U.S. Security Treaty and the commitment that the United States will go against any unilateral action that will infringe upon the administration rights of Japan.” Tetsuo Kotani, of the Japan Institute of International Affairs, observed that “this is an important step for the alliance and sends a strong message to Beijing that Washington stands firmly with Tokyo. . . . This is U.S. reassurance to Japan.”

In fact, assured of Washington’s commitment to come to Japan’s defense in case of a Chinese attack, Tokyo has adopted a more strident position in the dispute. In the 1970s, as Japan and China established diplomatic relations and signed a peace treaty, the conflict over the Senkakus was a sticking point. The two sides agreed to set the sovereignty question aside. But more recently, Tokyo has asserted that “Japan never recognized the existence of an issue to be solved on the territorial sovereignty over the Senkaku Islands” and did not make any agreement “about ‘shelving’ or ‘maintaining the status quo’ regarding the Senkaku Islands.”

The United States has been much more circumspect regarding the Philippines despite similar treaty obligations under a mutual security treaty. As tension between the Philippines and China spiked in late 2012, the State Department issued a statement: “We are concerned by the increase in tensions in the South China Sea and are monitoring the situation closely. . . . The United States urges all parties to take steps to lower tensions in keeping with the spirit of the 1992 ASEAN Declaration on the South China Sea and the 2002 ASEAN–China Declaration on the Conduct of Parties in the South China Sea.” In February 2013 the State Department spokesperson stated that “the United States supports the use of diplomatic and other peaceful means to manage and resolve these kinds of disagreements, including the use of arbitration or other international legal mechanisms.” The reticence to make a clear commitment to help Manila defend against an attack by China showed a clear reluctance to be entrapped in a military confrontation with China over Philippine’s claimed features in the South China Sea. The frankest expression of this reluctance was when a senior U.S. military official stated: “I’m pretty frank with people: I don’t think that we’d allow the U.S. to get dragged into a conflict over fish or over a rock. . . . [Despite a defense treaty], not allowing them to drag us into a situation over a rock dispute, is something I think we’re pretty all well-aligned on.”

In 1995, the spokesperson for the Department of State obfuscated on the issue of whether or not the mutual defense treaty with the Philippines was applicable to these maritime disputes. Fifteen years later, with growing concern about China’s assertiveness, Washington determined to clarify U.S. policy. With tensions escalating, Secretary of State Hillary Clinton reiterated U.S. policy, stating that “while the United States does not take sides on the competing territorial disputes over land features in the South China Sea”, but, pointing to China’s expansive claims, she added, “consistent with customary international law, legitimate claims to maritime space in the South China Sea should be derived solely from legitimate claims to land features.” The Philippines welcomed Washington’s more forceful statement, but still Washington made no linkage to treaty obligations. In November 2011, aboard the USS Fitzgerald while commemorating the sixtieth anniversary of the Mutual Defense Treaty, Secretary Clinton urged a peaceful settlement of disputes, but underlined the U.S. commitment to the Philippines, saying “we are making sure that our collective defense capabilities and communications infrastructure are operationally and materially capable of deterring provocation from the full spectrum of state and non-state actors.”

Perhaps encouraged by U.S. statements, in April 2012, in the midst of a standoff with China over Scarborough Shoal, Philippines Foreign Secretary Albert del Rosario stated that “In terms of U.S. commitment . . . they have expressed that they will honor their obligations under the Mutual Defense Treaty.” Manila has called for explicitly including the disputed islands in the United States–Philippines Mutual Defense Treaty, but the 2014 Enhanced Defense Cooperation Agreement left this ambiguous. The treaty only commits the United States to help defend the “metropolitan territory” of the Philippines and the “Pacific Area.” Beyond that, Washington has remained evasive on the extent of its commitment.