Ukraine succeeding against Russia in the war has become a question of U.S. credibility, Radoslaw Sikorski, Poland's foreign minister, told CNBC. "The success of Ukraine is now a matter of U.S. credibility. And if U.S. support for Ukraine were to stop, I think U.S. allies around the world would notice and would start hedging," he told CNBC's Steve Sedgwick Tuesday. Aid for Ukraine has become a highly contested topic among U.S. lawmakers in recent months, with an aid package that would see around $61 billion worth of support for the country currently being stuck in the U.S. House of Representatives. The bill was approved by the U.S. Senate in Feb