US President Barack Obama speaks with Attorney Genral Loretta Lynch in the Oval Office of the White House in Washington, DC, on January 4, 2016. (AFP Photo)
US Republicans clamored to paint North Korea's surprise nuclear test as yet another failure of Barack Obama's foreign policy on Wednesday, rounding on the outgoing president as he faced a stern new overseas challenge.
"Our enemies around the world are taking advantage of Obama's weakness," presidential contender Senator Marco Rubio said, blasting the 44th president for standing "idly by" as a "lunatic" leader in Pyongyang threatens international peace.
Another White House hopeful, Senator Ted Cruz, said the test "underscores the gravity of the threats we are facing right now and also the sheer folly of the Obama/Clinton foreign policy," referring to former secretary of state Hillary Clinton.
"When we look at North Korea, it's like looking at a crystal ball. This is where Iran ends up if we continue on this same misguided path."
Republicans vying to replace Obama in 2017 have accused him and Clinton -- the Democratic presidential frontrunner -- of lacking resolve.
They claim meekness and vacillation has created a void that the Islamic State group, Russia, China, Iran and now North Korea have stepped into.
"Dictators like Kim Jong-Un don't take time outs -- they take advantage when the US looks away," said House foreign affairs committee chairman Ed Royce.
Obama came to office in 2009 vowing to extricate the United States from costly foreign wars and signaling Washington would no longer rush headlong into every global crisis.
Administration officials say the policy is borne from a more steely-eyed approach to the US national interest.
The United States has imposed heavy sanctions on North Korea in response to Pyongyang's past nuclear and missile tests staged in violation of UN resolutions.