派遣特使、部署核潜艇，美国能否力压普京会晤泽连斯基？

Group 1 - The U.S. is threatening to impose "very severe" tariffs on Russia, with a deadline approaching on August 8, and high-level officials are visiting both Russia and Ukraine to discuss the situation [1][3] - The U.S. has deployed two nuclear submarines to "necessary areas," escalating nuclear deterrence rhetoric between the U.S. and Russia [10][11] - Russia maintains its stance on the Ukraine conflict, emphasizing territorial control and preventing Ukraine from joining NATO, while pushing for the demilitarization of Ukraine [5][6] Group 2 - Ukraine is focusing on stabilizing its domestic regime and adopting asymmetric warfare strategies, facing challenges due to U.S. military aid and European support being insufficient [8] - Diplomatic efforts among the U.S., Russia, and Ukraine are currently hindered, with potential for military conflict escalation [8] - Russia's nuclear capabilities are still a concern, with statements from officials indicating readiness to use them as a last resort [12]