A report issued by the UN on Friday detailing higher than expected levels of Iranian uranium enrichment constitutes a tipping point in negotiations to halt Tehran’s illicit pursuit of nuclear weapons.The report, issued on the heels of the second round of direct talks in Baghdad between members of the UN Security Council, Germany (P5+1), and Iran, is cause for concern. Coupled with the failure of the talks to result in a clear path forward, it confirms what Iran watchers already knew: no package of concessions will dissuade Tehran from its pursuit of a nuclear stockpile. Regime change in Iran is necessary, it is inevitable, and the window for diplomatic action is closing rapidly.But who will act? US President Barack Obama, consumed by domestic electoral concerns, appears intent to meet the Iran problem with silence. European calls for continued discussions cede precious time to the mullahs. Official Security Council claims of progress are increasingly suspect.The writer is the Director of the Negotiation and Conflict Management Program and Co-Director of the Global Affairs and Human Security program in the School of Public and International Affairs at the University of Baltimore. email@example.comThe menu of options available to avert a nuclear crisis is not exhausted but the time for action is now.A primer for US and Israeli action:-- US negotiators should promptly withdraw from further participation in direct talks, scheduled for next month in Moscow, unless Iran agrees to an immediate timetable for unfettered inspections by the International Atomic Energy Agency. The world cannot wait as threats gather or be held hostage to the posturing of a regime bent on the pursuit of weapons that further destabilize the Middle East, threaten the state of Israel, and challenge the emergence of democratic neighbors.-- If calls for nuclear transparency are rebuffed, the US and Israel should take joint responsibility for swift and immediate tactical strikes to downgrade Iran’s emerging weapons program. The strikes should minimize civilian casualties and they should be followed with a clear statement that any response by Tehran will unleash a fierce campaign to unseat and replace Iranian officials. -- To ensure future compliance with global norms of nuclear non-proliferation, economic and political sanctions on Iran must be enhanced and made more consistent. Diplomatic activity to build support for more severe sanctions should be framed as necessary to avoid a prolonged war and ensure Iranian compliance with negotiated concessions on the nuclear issue.-- Increased economic and political pressure should be tied to concrete proposals for substantive action and incentives for sustained adherence to transparency and the rule of law. Tehran cannot be afforded the privileges of a world power if it insists on negotiating in bad faith, dishonest diplomacy, and the violation of international law.-- The primary Iranian dissident organization in exile, Mujahedin-e Khalq (MEK), should be embraced as a strategic asset by western governments. MEK’s rejection of clerical rule, their non-opposition to Israel, their significant track record of organized opposition, and their willingness to share valuable intelligence about Iran’s nuclear pursuits should be affirmed with formal recognition. A string of broken promises to MEK by western governments should be reversed and efforts should be made to empower the group as an alternative to theocratic rule in Iran. Removing the group from the US State Department’s list of Foreign Terrorist Organizations is a first step but much more must be done to support this political movement that seeks grassroots change consistent with US and Israeli security interests. Signaling Tehran that MEK can no longer be used as a bargaining chip in a grand campaign to curry favor or stem proxy violence is a necessary step towards more meaningful future negotiations.Talks in Istanbul and Baghdad have left unresolved key issues, and those set for Moscow hold no more promise, but Iranian intent is now abundantly clear. Tehran’s reputation for dishonest diplomacy and their unmistakable efforts to use negotiations as a means of buying time for nuclear armament is confirmed. World powers now have a responsibility to act accordingly. What measures the P5+1 take next will have implications for whether Tehran engages in future negotiations seriously. How the US and Israel promote the inevitable matter of regime change is next up for consideration.The failure of diplomacy to curtail Tehran’s nuclear pursuits provides justifiable cause for action and the choice is unmistakably clear: Act now or prepare for a nuclear-armed Iran.