、。
US nuclear waste could become a target for terrorist attacks.
Literal
US [genitive-の] nuclear-waste, terrorist-attack [genitive-の] target [into-に] can-become.
A headline-style fragment. ~になりうる ('can become X,' 'might become X') is a formal/written modal expression built on the ancient auxiliary 得 (う, 'can'): ~ることができる → ~うる/~える (classical) → survives today in ~なりうる, 言いうる, 考えうる. Marks logical possibility rather than physical ability. Two dropped elements mark this as headline-ese: the topic particle は after the subject is missing, and the copula is absent at the end. 標的 ('target') is a slightly formal alternative to ターゲット or 的.