中方承诺......英语怎么说？

commitment n.

翻译时用倾向于用名词会显得比较正式.

Chinese government adheres to the commitment that China will not take an intiative to use nuclear weapons.

中方承诺决不首先使用核武器
China side pledged to no first use its nuclear weapons.

China agrees/promises not to use nuclear weapon first.

用commit
People's Republic of China commit itself not to be the first to use nuclear weapons.

pledge
.
n.保证, 誓言, 抵押, 抵押品
vt.
保证, 使发誓, 抵押, 典当, 举杯祝...健

应该是"promise(v.)"吧 ...