In addition, Mr. Trump’s goals remain unmet, and the U.S. military is running short on key armaments that it needs for global reach. With Mr. Trump’s aims shifting, Washington is losing credibility both militarily and diplomatically, analysts said. “For U.S. allies and those who rely on the U.S. for security, this is confirmation that you can’t trust the United States.” European allies remember Mr. Trump’s vow to seize Greenland from a NATO ally and his threats to leave the alliance unless other allies met his spending goals. Enemies more willing to suffer the pain and expense of conflict, as in Vietnam, Iraq and Afghanistan, outlasted the United States.