The White House was taken by surprise by Vladimir V. Putin’s decisions to invade Crimea, but also by China’s increasingly assertive declaration of exclusive rights to airspace and barren islands. Neither the economic pressure nor the cyberattacks that forced Iran to reconsider its approach have prevented North Korea’s stealthy revitalization of its nuclear and missile programs. …
“We’re seeing the ‘light footprint’ run out of gas,” said one of Mr. Obama’s former senior national security aides, who would not speak on the record about his ex-boss. …
Still, some senior officials who left the White House after the first term concede — when assured of anonymity — that Mr. Obama erred in failing to have a plan to back up his declaration that [Syrian] President Bashar al-Assad had to leave office.