By May 1990 the AFL had been forced back to Gbarnga, still under the control of Bowen's troops, but they lost the town to a NPFL assault on 28 May. By June 1990, Taylor's forces were laying siege to Monrovia. In July 1990, Prince Yormie Johnson split from Taylor and formed the Independent National Patriotic Front (INPFL). The INPFL and NPFL continued their siege on Monrovia, which the AFL defended. Johnson quickly took control of parts of Monrovia prompting evacuation of foreign nationals and diplomats by the US Navy in August.