What are the national security concerns raised by experts regarding Donald Trump's approach to Ukraine and NATO relations?

Former National Security Adviser John Bolton and other experts express significant concerns about Trump's approach to Ukraine, which they characterize as resembling dangerous appeasement tactics. The primary worries center on Trump's reluctance to support Ukraine's NATO membership and his willingness to negotiate through concessions that could compromise Ukrainian sovereignty. These strategic positions alarm European allies and raise questions about America's global leadership role. Experts warn that such missteps could weaken U.S. national security interests and damage longstanding international alliances, particularly at a time when Ukraine faces ongoing threats to its territorial integrity and democratic institutions.