Iran would enrich uranium to 56 percent in order to fuel boats and submarines if it needed to operate such vessels, the head of the country’s nuclear agency said Tuesday.

International treaties forbid countries from enriching uranium to 20% or higher, since that type of enrichment is considered too high for civilian usage and indicates it could be for military purposes.

Iran’s nuclear program has long been under international criticism, and heavy sanctions have been implemented by the US, EU and other countries in an attempt to stop Tehran from obtaining nuclear weapons capability.

At the moment Iran has “no enrichment plan for purity levels above 20 percent,” Fereidoun Abbasi told the FARS news agency. However, “certain needs” such as “ships and submarines” could cause Iran to make “small engines which should be fueled by 45 to 56 percent enriched uranium.”

“We have the capability to produce nuclear fuel for ships and submarines,” Abbasi said in July, when he first announced Iran had the knowledge and ability to fuel such vessels with enriched uranium.

Talks held between Iran and the world powers on the Iranians’ rogue nuclear program at the start of April did not yield any results, and Western officials said the sides were a “long way apart” on any deal.

Israel has said Iran is only a few months away from the threshold of having material to turn into a bomb and has vowed to use all means to prevent it from reaching that point. The United States has not said what its “red line” is, but President Barack Obama has said that it will not tolerate an Iran armed with nuclear weapons. In an interview on Israel’s Channel 2 on Tuesday, President Shimon Peres said he was “100 percent certain” Obama would use force to thwart Iran’s nuclear program if all else failed.

Any strike on Iran could provoke fierce retaliation directly from Iran and through its Middle East proxies in Syria, Lebanon and Palestine, raising the specter of a larger Middle East conflict.