Following a joint U.S.-Israeli strike that killed Iranian Supreme Leader Ayatollah Ali Khamenei on Saturday, the conflict has rapidly escalated across the Middle East, with Iran and Iranian-backed groups launching retaliatory attacks on Israel and U.S. military targets. 

Trump describes the campaign as the “last best chance” to address Iran's ballistic missiles and nuclear program and says it could last several weeks.

“The big question is the scope and the duration of the conflict,” Vice Adm. Robert Murrett (Ret.), professor of practice of public administration and international affairs, tells CBS News. “It's already expanded just a little bit in the last 24 hours, although the fact that the president has said he plans to talk to the new so-called leadership council, members of the leadership council in Iran, that might be illustrative,” he says.

“There've been estimates we've heard from different members of Congress and people in the administration, but none of those are probably accurate at this point, and the scope, whether or not it's going to be expanded further to some of the countries [the Emirates, Saudi Arabia, Oman] which surprisingly have been drawn into the conflict.”

In an interview with CBS News New York (beginning at 5:30), Murrett says, “Relative to the goal of regime change, I think regardless of your political background, I think everybody would like to see a different regime leading the Iranian people. The slaughter they did of their own civilians over the last couple weeks is evidence of that.”

Murrett adds, “Having said that, it's a difficult challenge and one that's probably going to take some time to play out.”