Their latest defiance will undermine his grand goal. He must act more forcefully.
Talks with Russia for further mutual reductions in their arsenals appear stuck. More important, the world's two outlier nations in an effort to prevent the spread of nuclear weapons – Iran and North Korea – are as defiant as ever against calls to rein in their nuclear ambitions.
Their obstinacy comes despite President Obama's willingness to talk to these two regimes with more openness and potential compromises than did the Bush administration.
Iran has now backed away from a recent offer to ship most of its low-enriched uranium to Russia for additional processing and eventual return as fuel for a civilian reactor. And North Korea said this week that it is reprocessing plutonium once again, which would allow it to make another atomic weapon. It had agreed in 2007 to disable its main reprocessing facility in exchange for aid.
These setbacks require Obama to engage more forcefully with other nations – especially China – to apply pressure on Iran and North Korea and possibly impose greater sanctions on them.