The United States' rebalancing to Asia, frequently described as a "pivot" to Asia, is unravelling.
The crisis in the Ukraine and the rise of the Islamic State in Iraq and Syria (ISIS) highlight the challenges posed to US policymakers as they seek to change American policy priorities to deal with the rise of Asia, especially China.
As then US secretary of defence Leon Panetta noted at the Shangri-La Dialogue in Singapore in June 2012, after the withdrawal from Afghanistan and Iraq and the drawdown of military forces in Europe, rebalancing will result in a shift from a 50:50 to a 60:40 ratio of US naval forces in the Asia-Pacific and Europe.
In practice, planned cuts in the defence budget would result in major reductions in defence spending.
Effectively, rebalancing meant that the US would maintain its current military presence in the Asia-Pacific while significant declines occurred in Europe.
Since the Cold War, America's status and interests as a global superpower resulted in American national security planners devising scenarios where the US faced conflicts simultaneously in Europe and Asia.
With the end of the Cold War, European states took a "peace dividend" and cut military budgets significantly, unlike the US.
This changed under the leadership of President Barack Obama. Faced with fiscal constraints arising from growing budget deficits, the increasing unpopularity in America of the wars in Afghanistan and Iraq, pressure for greater expenditure on health care, social services, domestic infrastructure and education as well as his own preference for a more low-key posture on defence issues, Mr Obama pushed for major US defence budget cuts.
In an era where resources were constrained, Mr Obama's rebalancing strategy made sense. It recognised that the US would have to make difficult choices as defence budgets were reduced.
Rebalancing could effectively occur only if American policymakers could focus their attention on the emerging challenges in the Asia-Pacific theatre.
The contemporary impact of television and the social media has meant that the onscreen execution of two American hostages by ISIS has suddenly had a major impact on domestic American opinion.
From opposition to further involvement in the internecine conflicts in the Middle East, aside from backing Israel, Americans now support a firm response to the rise of ISIS, or ISIL, the Islamic State in Iraq and the Levant.
On Sept 10, Mr Obama announced that the US will conduct a systematic campaign of air strikes against the ISIS forces, deploy 475 American personnel on the ground to provide training, intelligence and equipment to Iraqi and Kurdish forces, cut off the flow of funds and foreign fighters for the ISIS forces and provide humanitarian assistance to displaced civilians. The US will be supported by its allies in these missions.
THESE measures are the beginning of a new long-term American involvement in the Middle East. The irony is that the emergence of ISIS owes much to the disenfranchisement of Saddam Hussein's Baathist military and civil servants who were excluded by the American occupying force from any role in government. Their participation has provided ISIS with the capacity to act as a government and to fight like a conventional army.
The exclusion of Sunni tribes from any meaningful role in Iraq under Mr Nouri Al-Maliki's Shi'ite-dominated government resulted in tribal support for ISIS.
In war-torn Syria, President Bashar Al-Assad provided clandestine support as ISIS attacked Mr Bashar's Sunni opponents.
As ISIS expands its reach in Iraq and Syria and gains the allegiance of Sunni Muslim extremists globally, it will pose problems for governments around the world. Self-radicalisation as well as the influence of religious ideologues will lead young men and women to join ISIS.
Governments worry that fighters and explosives experts trained in Middle East battlefields will return to cause mayhem and carnage on the streets of cities in the West as well as in Asia.
Old conflicts take new form
THESE trends highlight the difficulty of making big strategic decisions.
While the US embarked on rebalancing to meet the challenge posed by a shift of power to Asia, especially China, old conflicts in the Middle East took new forms seen as threatening by the US.
Opinion polls shaped American policy initiatives and the important issues gave way to dealing with immediate concerns.
This pattern is also seen in Europe, resulting in a renewed American focus on Europe.
Russian President Vladimir Putin's takeover of the Crimea and the separatist rebellion in eastern Ukraine have revived Western fears of an expansionist Russia. The Nato summit in Wales on Sept 4 and 5 set the stage for a new Cold War with its support for sanctions on Russia.
Mr Putin's claim to protect ethnic Russians and Russian speakers outside Russia worries Russia's neighbours, even including those with strong ties to Moscow like Belarus and Kazakhstan as well as the Baltic and Eastern European states once part of the Warsaw Pact and now members of Nato. But the blame for these developments does not lie with Russia alone.
Russia has been suspicious of American (and European) intentions since the expansion of Nato to Eastern Europe in 1996, despite earlier assurances by president George H. W. Bush that Nato would not expand eastwards with the end of the Cold War.
In 2004, seven new members joined Nato, including the Baltic states which shared a border with Russia and were historically suspicious of Russia.
Western support for the overthrow of Ukrainian president Viktor Yanukovych and the European push for an exclusive association agreement that undermined existing eastern Ukrainian trading links with Russia fuelled Russia's masterminding of the separatist revolt in eastern Ukraine.
While Russia does not have the material resources to challenge the West and no longer has an ideological model attractive to alienated youth and emerging regimes, the US will have to expend time and resources to reassure its European allies facing a tense relationship with Russia.
If these new security concerns in the Middle East and Europe result in an American shift away from focusing on security issues in relationships in the Asia-Pacific, there may be a silver lining.
While the discussion on rebalancing has emphasised America's security challenges in Asia, especially in the context of a rising China, US interactions with the region are multifaceted, with diplomatic, economic, political as well as security dimensions.
The limits to the American defence pivot mean that American attention in the Asia-Pacific will focus on the economic and political opportunities in the region. This should result in a more balanced perception of American interests and role in the region.
More attention to these other dimensions could lead to a more cooperative relationship between the US and China, which would be a preferred outcome for states in East Asia.
Barry Desker is the Dean, S. Rajaratnam School of International Studies, Nanyang Technological University.