The Hashemite regime in Jordan has kept Israel's eastern border secure for over four decades, and has proven itself a comfortable partner with Israel on the Palestinian issue.
Nonetheless, the Hashemite regime is not necessarily immune to the Arab Spring. If it were to be deposed, who might succeed the regime, and can Israel be prepared for the outcome? The regime in Jordan is not perfect. It has refused to integrate its Palestinian majority, telling them they are merely refugees who should return to Palestine, and it is also is an autocratic regime that strips the majority of its citizens of their civil rights.
Nevertheless, Jordan has proven one virtue: It has kept Israel's longest borders safe and virtually worry-free for over four decades. Furthermore, it has been integrating a high-level cooperation on intelligence, counter-terrorism efforts and crime prevention with both the US and Israel.
Therefore, it is safe to say that the best arrangement Israel can ever possibly find along its borders is the current one, where the Hashemite family rules Jordan.
Nonetheless, the Arab Spring has proven that the strongest of dictators can fall to peaceful protests, and Jordan may not necessarily by an exception.
While the protests in Jordan have been quieter than those in other Arab countries, nonetheless they are regular and the protesters are constantly upping the ante, to the point where there have been open calls for toppling the king.
Should the king of Jordan be toppled, Israel will face limited options as to his successor. The Muslim Brotherhood in Jordan is dominated by Beduin Jordanians, not Palestinians, and yes, the Palestinian voting record in parliamentary elections shows they have been voting Brotherhood members out of office, to the point of electing none of them in 2010. Nevertheless, the Muslim Brotherhood is the most organized, well-financed and regionally-connected political organization in Jordan.
Common sense, then, indicates they will dominate the elections or at least have the strongest part in the new Jordanian government, just as was the case in Egypt, Tunisia and possibly soon Libya.
The Obama administration's attitude toward the Brotherhood isn't helpful, either. In fact, cables exposed by WikiLeaks show the US Embassy in Amman has been in touch with the Muslim Brotherhood.
BUT THERE is another strong contender: the PLO. The PLO is well integrated in Jordan; and is more accepted than the Muslim Brotherhood, especially are refugee camps. The PLO has the resources to dominate the public vote of a future democratic Jordan, but will that be good for Israel? The organization, which already dominated the Palestinian Authority, has been a thorn in Israel's side for almost two decades now, dragging it into painful negotiations that usually end up with Israel being asked to give more land for nothing in return.
Should the PLO take control of Jordan it will be in a much stronger position to hurt Israel politically and militarily. It is true that the PA under chairman Mahmoud Abbas has been able to bring terrorism under control in its territories, but on the political level Abbas and the PA have been harassing Israel ceaselessly.
Examples include Abbas's unilateral bid for UN Security Council recognition of the Palestinian Authority as a sovereign state, a breach of the Oslo peace agreement between Israel and the Palestinians.