West Bank annexation could also undermine Israeli alliances with Egypt and Jordan and alienate European military partners who have assisted U.S. missile defense efforts, leaving Washington alone to shoulder the burden.

The country that would be most directly impacted by Israel annexing the West Bank is Jordan. A major non-NATO U.S. ally, Jordan was long seen by Washington as playing a central role in the Israel-Palestine conflict and in regional security, following the peace treaty that Jordan signed with Israel in 1994.

Greenfield, criticized Israel's behaviour in the West Bank at a meeting of the UN Security Council on Wednesday. Thomas-Greenfield accused Israeli settlers of carrying out extreme violence against Palestinians in the territory.

ABC News’ Britt Clennett reports on how the second Trump presidency could impact whether Israel allows Jewish settlers to stake claims to disputed territory in the Golan Heights and the West Bank.