The Palestinian Islamic Jihad (PIJ) terror organization is often in the business of "jihad now, not later," an approach that has led to multiple deadly escalations between it and Israel in the Gaza Strip – even when this did not suit the immediate interests of Gaza's Islamist rulers, Hamas.

However, PIJ has recently been making a concerted effort not to undermine Hamas's rule, and has cooperated with Hamas's decision to seek a tactical, unofficial period of calm. What remains unclear is just how long PIJ will continue to play along before reverting back to its traditional role of arsonist.

Col. (res.) David Hacham, a former Arab-affairs adviser to seven Israeli defense ministers, and a senior research associate at the Miryam Institute, told the Investigative Project on Terrorism that relations between PIJ and Hamas as more complex than meets the eye. On the one hand, he said, they are united by the common Islamist cause of seeking Israel's destruction, and both are backed by the Islamic Republic of Iran.

On the other hand, Hamas "has a government role, and has to deal with a 2-million-strong population in Gaza. It has considerations to take into account that PIJ does not have to think about. PIJ is almost purely about jihad and terror," said the former Israeli defense official.