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.