The Obama administration is concerned Iran is on the verge of being able to enrich uranium at a facility deep underground near the Muslim holy city of Qom, which may strengthen those advocating tougher action to stop Iran’s suspected atomic weapons program.

Iranian nuclear scientists at the Fordo facility appear to be within weeks of producing 20 percent enriched uranium, according to Iran analysts and nuclear specialists who are in close communication with U.S. officials and atomic inspectors. Enriched uranium is used to fuel power plants and reactors, and may be further processed into atomic weapons material.

Administration officials speaking on condition of anonymity because of the sensitivity of the issue say Iran’s actions may bolster calls for military or covert action against the Persian Gulf country from Republican presidential candidates. It may also fuel pressure on the administration to impose measures approved by Congress to limit Iran’s oil exports.

“Senior advisers to President Obama privately express concern that Israel might see Iran’s commencement of the Fordo facility” as a justification for a military strike, said Karim Sadjadpour, an Iran analyst at the Carnegie Endowment for International Peace in Washington who has frequent discussions with the White House.

The U.S. and Israel have said military action remains an option if needed to stop Iran from acquiring a nuclear bomb, Bloomberg reported.