In the wake of the failed July 15 coup in Turkey, there is renewed debate over the security of some 50 US nuclear bombs stored at Incirlik airbase.

The Stimson Center, a Washington DC think tank, said in a report on Monday that the continued presence of nuclear weapons at Incirlik "raises serious risks of their seizure by terrorists and other hostile forces."

"Whether the US could have maintained control of the weapons in the event of a protracted civil conflict in Turkey is an unanswerable question," the report said.

Located only 70 miles (110 kilometers) from war-torn Syria, Incirlik is a major logistic hub for US military operations around the globe and a base for the US-led coalition against the "Islamic State" to conduct airstrikes in Syria and Iraq.

During the coup, US flights in and out of the base were temporarily halted. Afterwards, several top Turkish commanders at the base were arrested for their alleged role in the plot and power to the base was cut off for nearly a week.

And as some in Turkey blame the United States for playing a role in the coup, periodic anti-American protests have erupted around the base calling for its closure. Citing security concerns about terrorism, the Pentagon earlier this year evacuated the dependents of US service members from the base.

A volatile situation

Hans Kristensen, the director of the Nuclear Information Project at the Federation of American Scientists, told DW that political instability and the overall security situation in Turkey were reasons enough for the US to pull its nuclear weapons out.

"There is no other country in Europe where the US stores nuclear weapons where a military coup just happened and you have something that looks almost like a civil war with violent explosions and killings, and in addition to that you are less than 100 miles from the border of a completely war-torn country, Syria," he said.

"Those are security and political conditions that are completely out of sync with what you normally require for having nuclear weapons deployed," he added.

Worth the risk?

Over the past couple of years, the United States has  invested in adding additional security to safeguard its nuclear bombs at Incirlik, which are protected by US soldiers, stored in underground vaults and equipped with authorization codes.

However, the authors of the Stimson report question whether the military value of storing the bombs there is worth the risk.

"There are a lot of safeguards in place…but when you are talking about US nuclear weapons, if there is still a risk, you have to consider whether it is really worth taking that risk," report co-author Laicie Heeley told DW. "When we are talking about these particular weapons, the military value is not great enough to justify the risk you are taking."

The presence of US nuclear weapons - in particular variants of the B61 gravity bomb - at Incirlik is a relic of the Cold War. While most nuclear bombs were withdrawn from Europe in the 1990s, the United States maintains about 180 B61s in Turkey, Germany, the Netherlands, Belgium and Italy.

No military value

In addition to these forward deployed strategic and tactical nuclear weapons, the United States has submarine, missile and strategic bomber nuclear deterrents, raising further questions about whether the B61 is even necessary.

"Militarily the B61s have no real meaning in Europe. They were deployed at a time when there was a completely different security situation [on the continent]," Kristensen said.

Germany, the Netherlands, Belgium and Italy not only store the nuclear bombs but also provide aircraft that could deliver the payload. However, the usefulness of the B61s at Incirlik is questionable because the base essentially acts as a nuclear storage depot.

Turkey has no fighter wing squadron at the facility capable of carrying the B61 and doesn't permit the United States to permanently station its aircraft there for that purpose.

Symbolic security assurance

The main argument for maintaining nuclear weapons in Europe and Turkey is to show the United States' commitment to NATO members. This nuclear assurance has gained greater weight amid heightened tensions between the West and Russia.

Pulling nuclear weapons out of Incirlik now might make Turkey feel abandoned by its allies at a time when US-Turkish relations have hit a low point.

"While the withdrawal of tactical nuclear weapons from Europe has been an ongoing debate, withdrawing them from Turkey at this time may be over interpreted and perceived as a downgrading of the relationship," Ozgur Unluhisarcikli, the director of the German Marshall Fund in Ankara told DW.

However, given that there is little military value in the B61, experts say resources could be better used by focusing on conventional forces to reassure NATO members.

"The B61s don't serve a military role in Europe… [withdrawing them] wouldn't hurt NATO security and may even help NATO security by focusing on conventional forces," Kristensen said

Heeley agreed.

"The US in the past couple of years has invested significantly in [NATO]; they have put a lot of new conventional resources into the alliance," she said. "The US should be able to show its support to Turkey in other ways through conventional support."

Pentagon waste

The Stimson report was part of a broader assessment of the Pentagon's modernization program of the nuclear triad, which by some estimates could cost up to $1 trillion (890 billion euros) over the next three decades.

The authors argue that given the questionable military value of the B61 and the diversion of aircraft resources, they should be removed from Europe in order to cut costs and allow fighter squadrons to focus on conventional roles.

They called the $8 billion multi-year effort to update and extend the life of the B61 a "particularly egregious example of waste."