He is most compelling about poverty when he's talking about it as a national obligation - what he calls "the moral issue of our time."
Argentines partake as if it were a national obligation.
"You cannot blame Doordarshan; it had a national obligation."
There is no national obligation for Hamilton to help Armstrong, or vice versa, just because they have the same nationality.
The PSO has been meeting the country's fuel needs by merging sound business sense with national obligation.
Dual nationals may also be subject to Yemeni national obligations, such as taxes or military service.
Taking care of them now is a national obligation.
"But I believe we have a national obligation to insist upon responsible fatherhood."
Clearly, maintaining this critical artery is a national obligation.
We are gratified by this demonstration that an independent scientific organization will rise to meet its national obligations.