Iran scientist's murder and U.S. troop drawdowns could leave Biden with an even thornier Mideast

Myriad challenges await Biden in Middle East
Myriad challenges await Biden in Middle East 02:25

Northern Iraq — There's been an outpouring of grief in Iran and vows to take revenge for the life of nuclear scientist Mohsen Fakhrizadeh, who was gunned down in an ambush last week. Iranian President Hassan Rouhani blamed Israel for the killing on Saturday. Israel hasn't commented.

Rouhani said his country would take revenge "in due time" — but wouldn't fall into a trap.

Body of slain top Iranian nuclear scientist to be buried
Mourners sit next to the coffin of Iranian nuclear scientist Mohsen Fakhrizadeh, during the burial ceremony at the shrine of Imamzadeh Saleh, in Tehran, Iran November 30, 2020. WANA NEWS AGENCY/Reuters

That was likely a reference to hopes in Iran that President-elect Joe Biden will re-join the 2015 nuclear agreement that gave Iran relief from international sanctions in return for restrictions on its nuclear activities. President Trump pulled the U.S. unilaterally out of the international pact in 2018, prompting Iran to renew its atomic research and uranium enrichment in violation of the deal's terms. 

Fakhrizadeh was killed in what appeared to have been a well-planned and coordinated, military-style attack. It happened almost 10 years after Tehran accused Israel of assassinating another nuclear scientist, and some suspect the latest killing was an effort to provoke a response from Iran, which has allied militias across the Mideast capable of targeting Israeli and even U.S. forces and interests.

Iran blames Israel for scientist’s killing 01:39

But at one base in Iraq, where American forces help coordinate airstrikes against ISIS targets in the region, officers told us their threat level hasn't changed — over Iran's threat for revenge, or a looming change in the U.S. deployment. 

The Pentagon announced this month that troop numbers in Iraq would be cut by 500 just before President-elect Biden takes office. General Ryan Rideout told CBS News it wouldn't impact operations. 

"I think we're capable. I don't think you'd really see much of a difference," he said.

But critics of the troop drawdown say it could be a boost to the Iranian-backed militia groups that have already fired scores of rockets at U.S. targets in Iraq this year. 

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Across the border in Syria, the fight against ISIS still isn't over, nearly two years after the extremists lost control of their last patch of territory. We flew with U.S. troops over a sprawling camp where more than 60,000 Syrians are living, displaced by the simmering war

The U.S. Army's 82nd Airborne Division is on the ground patrolling the desert in the area. It's thought that thousands of the ISIS extremists are still at large. Some may have mixed back into the population after the group's self-declared "caliphate" crumbled. 

The point of the patrols is to stop ISIS from regrouping and gaining a new toehold in the villages scattered across the dusty terrain. 

Islamic State a year after its leader was kil... 07:47

Lieutenant Colonel Val Moro told CBS News that his troops are trying to persuade locals that the U.S. will stick by them in the long fight against ISIS. 

"We're not going away until they're gone, that's the bottom line," he said. 

But following President Trump's decision last year to open the door for an incursion by Turkish troops into Syria, some locals said they can't trust the U.S.

That won't make things any easier for President-elect Biden when he takes office in January and inherits a plethora of problems in what was already an unstable, war-torn part of the world.