U.S. government officials have grown alarmed that the Haiti National Police could begin to crumble within hours — and that a long-planned multinational mission led by Kenya to provide reinforcements may not be enough to save the country from a complete descent into gang control. Outgunned Haitian police have been battling a united front of gangs and losing key firefights. Now, a potential power void and a collapse of the Haitian government that had already faced a skeptical public risks undermining whatever morale is left among the police forces. “The government could fall at any time,” a U.S. official told...