There are a number of lessons to be learned from the nearly total collapse of Iraqi forces in the face of the offensive launched by the al-Qaida-affiliated Islamic State in Iraq and Syria (ISIS). As Prime Minister Binyamin Netanyahu pointed out in a speech at the Institute for National Security Studies on Sunday, these lessons have a direct and negative impact on the possibility of negotiating a deal with the Palestinians that would result in the creation of a Palestinian state on the West Bank.First, US-trained Arab forces are unreliable in times of crisis. Israel’s national security leadership has watched in recent weeks as a few thousand ISIS terrorists overran Iraqi security forces that were trained and armed over the course of five years by the US military at an expenditure of some $25 billion.This has direct implications for Israeli-Palestinian security arrangements. Last December, when negotiations orchestrated by US Secretary of State John Kerry were under way between Israel and the Palestinian Authority, one of the main obstacles was the Jordan Valley.Kerry proposed a security plan that would ultimately remove the IDF from the valley. In its place, an international force, trained by the US, would be stationed on the border with Jordan.What has happened in Iraq has vindicated Israel’s opposition at the time to Kerry’s proposal. If Sunni security guards in service to Iraqi Prime Minister Nouri al-Maliki’s Shi’ite government failed miserably against ISIS, there is little hope that a US-trained Arab force in the Jordan Valley would successfully fight fellow Arabs to protect a Jewish state.“No one can guarantee the security of the State of Israel except the IDF,” Netanyahu declared. “We can no longer trust that local forces trained by the West will curb and stop the Islamic penetration.”Second, ISIS’s surprising success in Iraq is now directly threatening Jordan. King Abdullah II’s government has put the country’s border guard on alert, reinforced troops along its 230-kilometer border with Iraq, and added tanks and armor to thwart any move in Jordan by ISIS militants, who have seized a string of cities from northern Syria to western Iraq.No less troubling to the Amman government are signs of support for ISIS inside Jordan. In the impoverished city of Maan, located about 200 kilometers south of Amman, demonstrators waved the ISIS flag and shouted “Down, down with Abdullah.” The Muslim Brotherhood also has a strong presence in Jordan, where Palestinians are the majority of residents.Both the US and Israel have an interest in maintaining political stability in Jordan. According to The Daily Beast, Israel and the US are cooperating with Jordan to prevent ISIS forces in Iraq and Syria from infiltrating Jordan’s borders. Nevertheless, the stability of Hashemite rule in Jordan can no longer be taken for granted.Conventional wisdom used to be that, with the demise of Iraq’s brutal dictator Saddam Hussein, one of Israel’s most powerful enemies had been neutralized and Israel no longer faced a threat from its eastern border.But with the deterioration of Iraq and the potential for instability in Jordan, the existential threats presented by a Palestinian state on the West Bank are once again very real.Netanyahu said that plans to build a security barrier along the eastern border would continue. And while it would not prevent rockets and missiles, and tunnels could still be dug underneath it, the barrier would still make it much more difficult for terrorist groups to infiltrate Israel.The idea that territory controlled by a “moderate” Palestinian political leadership can be taken over by Islamist extremists is not a theoretical scenario. In 2007, the US-backed Palestinian Authority’s security forces – numbering 12,000 men – were overcome by about 3,000 highly motivated Hamas fighters.Palestinians have insisted that any future Palestinian state must also include the Jordan Valley. But this is a demand that Israel will find impossible to meet, considering the new realities on the ground in Iraq, Syria, and Jordan. As Netanyahu noted, maintaining an IDF presence in the Jordan Valley and the Palestinian territories is not incompatible with Palestinian sovereignty. A failure to maintain such a presence, on the other hand, would likely precipitate the collapse of the Palestinian Authority.