Last week, while meandering toward a fourth U.N. Security Council sanctions resolution against Iran, Washington was blindsided by the revival of a previously discarded plan to enrich some of Iran's uranium to higher levels for use in the Tehran research reactor. This proposal -- a good deal for Iran when it was proposed last year by the misguided Obama administration -- is even better in its latest iteration and does nothing to stop Iran's uranium enrichment program.

The Iranian enrichment deal was brokered by Brazil and Turkey, two of the 10 current nonpermanent Security Council members, and it could pose difficulties for getting the council to adopt another resolution on sanctions. To forestall the debilitating effects of the Brazil-Turkey deal, Secretary of State Hillary Clinton promptly circulated to other council members the draft of a sanctions resolution the five permanent members and Germany had spent months negotiating.

Unfortunately, the damage was done. Turkey announced that negotiations on sanctions should cease for 30 days and Brazil flatly proclaimed it would not even discuss the draft resolution. Since one good turn deserves another, China and Russia will now graciously acknowledge the Brazil-Turkey initiative and insist that the other permanent members enter serious consultations regarding the draft of the permanent five. Thus, having negotiated intensely for months with Russia and China, Mrs. Clinton can look forward to another opportunity to negotiate intensely with both them and their surrogates.

The pending, wholly inadequate sanctions in the draft resolution will almost certainly grow weaker. Most significantly, a new effort to embargo major conventional weapons sales to Iran does not prohibit selling Iran air defense capabilities. Thus, Russia can still deliver its sophisticated S-300 system, which can defeat a possible Israeli air attack on Iran's nuclear program and could readily be used against U.S. planes if Iran later threatened U.S. forces in the Persian Gulf.

In addition, key Russian entities, including Rosoboronexport, its international arms-sales agency, were released from unilateral U.S. sanctions as part of a desperate effort to get Moscow's support. According to some press reports, China received analogous treatment, including avoiding sanctions for nuclear deals with Pakistan.

This is where South Korea's conclusion, announced Friday, that the North had torpedoed its corvette Cheonan in an unprovoked attack, complicates President Obama's life. Mrs. Clinton has several times since then properly supported Seoul and talked tough about responding to Pyongyang's breach of the 1953 Armistice Agreement. Washington and Seoul must react vigorously.

Although not directly related to the sinking of the Cheonan, the U.S. should again declare the North as a state sponsor of terrorism, reversing one of the Bush administration's most shameful acts in delisting it. South Korea should end all economic activity in the North, and the U.S., Japan (also currently a nonpermanent Security Council member) and South Korea should demand that the council ratchet up existing North Korea sanctions. Joint defensive military preparations, just announced, are also appropriate.

Former U.N. Ambassador John Bolton, is a Fox News contributor and a senior fellow at the American Enterprise Institute, is the author of "Surrender Is Not an Option: Defending America at the United Nations" (Simon & Schuster, 2007). To continue reading his column in The Wall Street Journal, click here.

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