By Mike StoneWASHINGTON (Reuters) -The Trump Administration's desire to send long-range Tomahawk missiles to Ukraine may not be viable because current inventories are committed to the U.S. Navy and other uses, a U.S. official and three sources said. The official said the U.S. may look into allowing European allies to buy other long-range weapons and supply them to Ukraine, but Tomahawks were unlikely. The U.S. decision to help Ukraine target Russian energy infrastructure appears to be one tangible outcome of the new stance. Advertisement AdvertisementAdvertisement AdvertisementA new financial mechanism, the Prioritized Ukraine Requirements List (PURL), has been developed by the U.S. and allies to supply Ukraine with new weapons and those from U.S. stocks using funds from NATO countries. Russia said on Monday that its military was analyzing whether or not the United States would supply Tomahawk cruise missiles to Ukraine for strikes deep into its territory.