UNRWA should be defunded (and certainly not supported by the US) because it has allowed rockets to be stored in its schools in Gaza. Moreover, UNRWA sponsors terrorism by giving such rockets to the police force in Gaza: http://www.thedailybeast.com/articles/2014/07/20/did-the-united-nations-...
The US government should not support organizations that directly or indirectly support terrorism. The US should not make any payments to UNRWA and should urge that UNRWA should be dissolved.