WASHINGTON (Reuters) -The Pentagon has been quietly blocking Ukraine from using U.S.-made long-range Army Tactical Missile Systems (ATACMS) to strike targets inside Russia, limiting Kyiv's ability to employ these weapons in its defense against Moscow's invasion, the Wall Street Journal reported on Saturday, citing U.S. officials. The news came as U.S. President Donald Trump has grown more frustrated publicly over the three-year-old war and his inability to secure a peace deal between Russia and Ukraine. After his summit with Russian President Vladimir Putin and a subsequent meeting with European leaders and Ukrainian President Volodymyr Zelenskiy failed to produce observable progress, Trump said on Friday that he was again considering slapping Russia with economic sanctions or, alternatively, walking away from the peace process.