Forget nukes and battleships.Washington may increasingly flex its geopolitical muscle in 2015 using an unconventional weapon: finance."Access to the US marketplace and US banks, and Washington's ability and willingness to use them, are becoming more important as instruments of foreign and security policy," Eurasia Group's Ian Bremmer writes. "There is no better example of this trend than the weaponization of finance 'the systematic use of carrots (access to capital markets) and sticks (varied types of sanctions) as tools of coercive diplomacy."The most talked-about examples, of course, are the sanctions imposed against Russia, and more recently, North Korea.But there are less obvious weaponizations of finance, too, such as "large-scale measures against financial institutions (mostly European banks) that help finance international entities under US sanction," writes Bremmer.However, Washington's "weaponization of finance" strategy has major drawbacks:The biggest near-term problem looming is soured relations between the US and Europe."Europe will become more frustrated with an American unilateralism that Europe (and European banks) must pay for. Also, the US could well slap new sanctions on Russia and/or Iran, eliciting a backlash in 2015," writes Bremmer.The next major issue is that others ' especially east Asia ' will begin to diversify away from the almost-too-strong dollar. "China has the muscle and the motive to create its own institutions, and where there is less dollar-denominated debt to complicate the process," writes Bremmer.The third problem is that the US firms will face increased risks of retaliation: everything from regulatory harassment to contract discrimination to cyber-attacks, writes Bremmer.Specifically, the US financial sector ' which has already gotten hit by cyberattacks ' could get really hammered.Finally, although Bremmer doesn't touch on this fact, numerous studies have shown that economic sanctions are ineffective.This has been argued by everyone from Robert A. Pape in a major paper for International Security titled"Why Economist Sanctions Do Not Work" toCarla Anna Robbins, an adjunct senior fellow at the Council on Foreign Relations.Although the "weaponization of finance" is a way to exert force without direct military conflict, the US risks further complicating political relations. And the strategy may only see limited success.SEE ALSO:The 10 Biggest Risks The World Faces In 2015Join the conversation about this story Click here to read full news..