In less than a week the Quartet meets. The Middle East Quartet—consisting of the EU, the UN Secretary General, Russia, and the United States—is supposed to gather on April 15, having postponed a planned March meeting.

The first priority for the Quartet should be a fierce denunciation of terrorism. Since the last Quartet meeting on February 5, savage acts of terror against Israelis have occurred. The first was the murder of a family of five, including three young children, on March 11. The Quartet issued a statement on March 13 condemning these murders but must do so again when Quartet principals, including Secretary of State Clinton, meet face to face next week. On March 23, a bus stop bombing in Jerusalem killed one person and wounded dozens more. Most recently, on April 6, Hamas fired a laser-guided missile at a school bus. According to the New York Times, officials of Hamas acknowledge that the targeting of a clearly marked yellow school bus was deliberate. One child was severely wounded, and had the missile struck just minutes earlier dozens would have been wounded or killed.

This is a grave escalation by Hamas, and its timing is noteworthy. The school bus attack came just a week before the Quartet meeting. Moreover, it came a week after unity talks between Hamas and Fatah and just days before additional talks are to begin. Hamas is making clear its terms for unity: a continuation of terror. In the past weeks, Hamas and other terror groups in Gaza have shot hundreds of missiles and rockets into southern Israel.

So the second priority for the Quartet should be clarity about the terms for Palestinian unity. Hamas participation in the government should be permitted only if Hamas accepts the “Quartet Principles” adopted in 2006 after Hamas gained a victory in Palestinian parliamentary elections. The Quartet stated that “all members of a future Palestinian Government must be committed to non-violence, recognition of Israel, and acceptance of previous agreements and obligations, including the Road Map.” Those three “Quartet Principles” were later endorsed by UN Security Council resolution 1850 (in a 14-1 vote, with only Gaddafi’s Libya opposing). It should be obvious after the school bus attack that Hamas does not meet these conditions, and the Quartet should therefore oppose any unity agreement with it. Far from renouncing and abandoning terror, Hamas is increasing it.

There has been considerable speculation about the Quartet presenting the outlines of a peace plan. It should be obvious to the Quartet that if the Palestinian Authority chooses unity with terrorists, progress toward peace is impossible. A Fatah/Hamas unity government cannot be a negotiating partner for Israel. For the Quartet to present or outline peace terms without making this crystal clear would be immoral, for in this case silence would indeed be consent—consent to the participation in the Palestinian Authority government by terrorist groups who have just days before made their contempt for peace manifest. It would also be very foolish, for Secretary Clinton must know that Hamas participation in the PA would create enormous legal problems under our counter-terrorism laws, as it did after the 2006 elections, and would doom her chances to get Congress to continue financial aid to the PA.

Recent World Bank and IMF reports detail the progress made in the PA on numerous important governance issues. Now the PA must choose, between continued progress toward statehood or unity with terrorists. And the Quartet, if it is to advance its goal of Palestinian statehood, must use its meeting next week to state clearly that the PA can choose a unity government with Hamas or progress toward statehood—but it cannot have both.