More than 100 Kenyan police arrived in Haiti's capital on Thursday to reinforce a security mission whose future has been in limbo, after the U.S. froze some funding before passing a waiver to unlock a separate batch of funds.

The mission, which began last year, is struggling with a lack of funding and personnel as gangs that control 85% of the capital, Port-au-Prince, keep seizing more territory.

The United Nations says that the U.S. has given notice that it is halting funding to a U.N.-backed mission in Haiti tasked with fighting gangs trying to seize full control of the country’s capital.