The reconciliation agreement announced between rival Palestinian factions Fatah and Hamas on April 23 is a severe setback for peace prospects and a slap in the face for Secretary of State John Kerry, who had devoted months of effort to reviving the fragile Israeli–Palestinian peace negotiations.

Fatah (the dominant faction within the Palestine Liberation Organization) and Hamas (the Palestinian wing of the Muslim Brotherhood) have long been bitter rivals. Although Fatah’s Yasser Arafat signed the 1993 Oslo Accords that established a framework for negotiating a peace treaty, Hamas not only rejected peace negotiations but remains committed to destroying Israel.

Hamas—designated as a terrorist organization by Israel, the United States, and the European Union—narrowly defeated Fatah in 2006 elections before seizing power in Gaza in a bloody 2007 coup.

Since 2005, Hamas and other Gaza-based terrorist groups have launched over 8,000 rockets into Israel, provoking two Israeli counteroffensives in Gaza in 2008 and 2012.

Hamas has been weakened by the growing unpopularity of its harsh rule, the July 2013 ouster of Mohamed Morsi’s Muslim Brotherhood regime in Egypt, and strained relations with Iran, its foremost foreign supporter. A decline in Iranian financial support due to differences over the Syrian civil war and Tehran’s sanctions-related economic problems has left Hamas unable to pay the salaries of its officials.

Fatah’s leader, Mahmoud Abbas, has also been weakened by his failure to deliver Palestinian statehood through an end run around negotiations with Israel by appealing to the United Nations.

The latest reconciliation effort between Fatah and Hamas has been motivated by weakness on both sides. Both factions seek to bolster their sagging popularity by a show of unity that appeals to Palestinians who have grown tired of factional clashes.

Reconciliation agreements had previously been reached in 2007, 2011, and 2012, but all went unimplemented due to endless bickering over how to share power.

But regardless of whether the latest agreement successfully yields a government of national unity, the sudden announcement of an “agreement in principle” to do so has exploded the current round of peace negotiations.

Israel suspended participation in the U.S.-brokered talks with the Palestinian Authority (PA) on Wednesday, with Prime Minister Benjamin Netanyahu warning: “Does [Abbas] want peace with Hamas or peace with Israel? You can have one but not the other. I hope he chooses peace. So far he hasn’t done so.”

The Obama Administration should reinforce this warning to prevent Abbas from inviting Hamas to join the PA. As long as Hamas remains wedded to terrorism and works for Israel’s destruction, this would deal a fatal blow to the comatose Oslo peace process.

U.S. law mandates that no American aid can be provided to the PA unless its members continue to recognize Israel, reject violence, and comply with previous Israeli–Palestinian agreements. President Obama and Secretary Kerry should make it clear that if Abbas continues to reconcile with Hamas terrorists, he will lose U.S. aid and jeopardize the survival of his own regime.