Although currently, classical realism theory based purely on power examination is under increasing criticisms. There is no denial that the power of a state is still a useful, if not the most fundamental, variable while assessing or predicting its behavior. The meaning of power has been extended since the further development of international studies. It contains traditional elements of power such as military, economic capability and also alleged soft power as a new emerging concept. The power talked about here is relative power of states rather than absolute power, which is the relative position in distribution of power. While at the same time, other plausible explanations of states’ behavior emerged separately or interdependently and they are all conducive for the creation of theories which have considerable explanatory power. Some of the various substitutes include inneapolitik which underlines the dominance of internal political process in foreign policy decision-making and the theory which emphasize on international institution [Rose (1998)]. However, in my perspective, all these theories didn’t threat the fundamental position of power, for more or less they are all associated with it. Anyway, no matter how the concept of power evolutes or other theories boom, power remains its core position in determining the behavior of states.
States’ external behavior aims at serving their national interests. Why power of states

matters in their external behavior? Firstly, power of a nation determines its national interest [Telhami (2002)]. When great power declined from its acme, the national interests change simultaneously [Rose (1998)]. Secondly, power determines the resources which the states’ external behavior can take advantage of [Mastanduno,
Lake and Ikenberry (1989)]. According to Toward a Realist Theory of State Action, two functions of states are mobilization and extraction while the latter means consumption of wealth and creation of power. Power constitutes the basis of states’ capability and furthermore, its influence on international stage. This does not necessarily bring the consonant adjustment in foreign policy immediately because of the existence of path dependency or stickiness. For instance, when British Empire apparently lost its previous predominant position in early 1900s, it still maintained its commercial and financial policy and colonialism for decades. Even in the year of
1956, in the aftermath of Second World War, in which Britain had been weakened profoundly, British launched military operation to reseize Suez from Egypt, its former colony and independent nation state at that time. This war ended with a shameful failure for once-great Britain, directly resulted from its relative decline compared with
US and USSR. Not until 1960s, Britain adjusted its East of Suez policy. This digressiveness of power and external behavior also occurred in the Concert of Europe, when the Hapsburg Empire, under Prince Metternich, played a more significant role than that consistent with its real power. Nonetheless, this digressiveness is limited.
There are two directions for corroborating the power's role in shaping the state's

behavior. Firstly, changes of relative power of states must end up with the changes of their behaviors. Secondly, the states with similar position in the distribution of power should behave homogenously.
To start with, I will demonstrate the first with the apparent historical reality. Although the inevitability of China’s surpassing of US is still an issue of agree to disagree. The relatively rising of China in the last quarter of 20 th century and the first decade of 21 th century is undeniable. This rising naturally resulted in the change of China’s behavior.
The foreign policy of state is to serve its national interests while these interests expand with their power. In other words, different distribution of power alters the preference of states [Telhami (2002)]. China’s economic boom facilitates a more beneficent position of China in distribution of power. Along with this process, China’s economic interest has been expanding globally and provided the need for converting its foreign policy. We have eyewitnessed the Chinese navy fleet appear in Somalia waters due to the fact that many goods shipping through this waterway are coming from or heading to China. Furthermore, the appearance of Chinese navy has another obvious premise, China once again possess a blue navy since the debacle in First
Sino-Japanese War of 1895. This fact leads to the other assertion: power determines the resources for the states’ external behavior. China’s foreign policy is based on this materials power and further protects and pursues its national interests. Likewise, the limitation of its power naturally constrained its foreign policy options. In a unipolar world under US hegemony, China has to cooperate with US and stay inside the extant

international institution even if this institution restrains China to some extent [Glosny
(2010)]. Even in the aftermath of financial crisis, the BRICs emerge as an influential and representative group; its cooperation is still limited especially in political issues for the combination of their power is much lower than that of US [Glosny (2010)].
Another case is Canada. Canadian military was a decent power in Second World War with a third largest navy, and participated in several important battles in Europe. After the Great War, Canada became a robust partner in UN and vigorously participated in almost all UN peacekeeping missions [Murray, McCoy (2010)]. In contrast, as Robert
W. Murray and John McCoy argued in their article From Middle Powers to
Peacebuilder: the Use of the Canadian Forces in Modern Canadian Foreign Policy that the contemporarily, Canada is even not capable for fulfill its mission of counterinsurgency and state-building in Afghanistan [Murray, McCoy (2010)]. This decline on military ability and descending participation and voice in UN missions, symbolized by the lack of Canadian senior commanders in UN peacekeeping mission headquarters[Murray, McCoy (2010)], is associated with its decline on relative power in the second half of 20 th
century and first decade of 21 th
century compared with developing countries [Doran (2005].
Subsequently, the states with similar position in global distribution of power should have homogenous pattern of behavior. The comparison need to be contemporaneously, because states in different time have diverse variety of options. Thus it excludes the comparison of hegemonies. The coeval great powers share common characteristics in

their states’ behavior while diverse significantly in political regime, internal politics process and other factors which considered being dominant in states’ external behavior by other schools of international studies. BRICs are all emerging great powers with considerable huge differences in culture, ideology, political regime etc.
Among BRICs, India is the largest democracy; China is an authoritarian regime to some extent, currently Russia is an alleged democracy that heavily depends on a charismatic leader, Brazil has a history of military regime until 1985. And the four countries have more differences on culture background than common. Still, the
BRICs behave similarly and concertedly in many aspects. These shared patterns of behavior result from their similar position in distribution of power [Glosny (2010)].
BRICs cooperate mainly in economic area and this cooperation is not targeting on remaking the present order. They are trying to expand their influence in the existing institutions which was established by US after WW II . Besides, mutual relationship with US is more important for each of BRICs than their inner mutual relationship
[Glosny (2010)]. The boundary between middle and small powers is ambiguous and dubious, thus I pick up the most classical representative of middle and small powers.
The classification of power states is based on their hard power, middle powers possess powerful economy. For existing middle powers covered in readings such as Canada,
Australia and South Korea are all alliance of current hegemony and supporter of existing international order [Hundt (2011)]. The security practices these three middle powers pursue in each region are all based on their military alliance with US.
Simultaneously the basis of the regional order is the economic interdependence with

US strengthens by FTAs [Hundt (2011)]. Furthermore, there are many common grounds for middle powers’ behavior. Including their positive attitude and active participation of UN; using their influence to benefit the development of international society, etc. They are catalysts of new initiatives, facilitator of coalition and manger of extant institution [Hundt (2011)]; rhetorically they are the model citizen in international community [Gecelovsky (2009)]. Small powers are the last part we focus on in this paper. The definition of small powers is highly various except basic consensus on their regional-focus foreign policy along with their regional interests and their highly concerns on keeping their independence both politically and economically. The small powers may profoundly influenced by the interaction of greater powers but this process doesn’t work in opposite direction. They are more often bandwagon than trying to balance the great powers because their own power is too limited to influence the situation. Thus the small powers exacerbate imbalance and they are insignificant in the distribution of power [Fox (1959)].
In the last paragraph, I’ll illustrate some other theories’ doubts on power’s position in state behavior and refute them in the following to make my argument more convincing. Firstly, the inneapolitik theory regards domestic factors as the fundamental variable in shaping the state’s behavior, during the process of which ideology, national character, partisan politics and socioeconomic structure decide the foreign policy [Rose (1998)]. Nevertheless this school lacks explanatory power when examining the international politics reality in which states with different internal

characteristics behave similarly. Secondly, states’ perception may determine the behavior, as the final decision is made by the attorney of state, the leaders, thus the perception of them is the real factor to decide their judgment than the actual reality
[Rose (1998)]. Meanwhile, in the power transition theory, political scientists argued that it is the dissatisfaction, which is also a perception, rather than power balance leads to the war [Lebow, Valentino (2009)]. This theory won’t weaken the position of power since perception is extracted from the power reality. The only difference is there is precise or fallacious perception of the power reality. The third theory underlines the effect of international institutions. But it also failed to explain the real world when US invaded Iraq without the mandate from UN Security Council and even the supports from many important alliances. The international institutions are still not capable of determining the behavior of hegemony and great powers while they have slight constraint on them indeed.