Final answer:
One major ongoing obstacle to peace between Israel and Palestinian Arabs is the mutual distrust and unwillingness to disarm or condemn violence, alongside issues such as control of Jerusalem, and the external influences like the US's support to Israel and the Fatah-Hamas divide.
Step-by-step explanation:
An on-going obstacle to peace between Israel and Palestinian Arabs is the deeply rooted mutual distrust and unwillingness to disarm or unequivocally condemn acts of violence by their own supporters. This has been a persistent issue since the breakdown of the Oslo Accords, which attempted to achieve peaceful coexistence and discuss the creation of a Palestinian homeland. Furthermore, complicating factors include disagreements over mutual recognition, borders, security concerns, water rights, control of Jerusalem, Israeli settlements, Palestinian incitement to violence, and solutions for Palestinian refugees.
The situation is further strained by external factors such as the high levels of financial and military support Israel receives from the United States, and the influence of oil revenues in Arab countries that support the Palestinians. Additionally, there is a lack of unity among Palestinians themselves, evidenced by the political divide between Fatah and Hamas. All these factors contribute to a volatile environment that hinders the prospects for a sustainable peace.