A report has slammed planned upgrades to the U.S. tactical nuclear bomb program as an "egregious" waste of money and said deployment overseas is risky, although experts point to benefits for allies in Asia.

The Stimson Center, a U.S.-based think tank, said Monday that scrapping all B61 bombs could save the U.S. more than $6 billion, adding that Washington could make Europe safer by withdrawing them from bases in foreign nations.

"The continued presence of these weapons at five sites in Europe, particularly in Turkey, raises serious risks of their seizure by terrorists or other hostile forces," the report said.