For months, Kyiv slogged through peace talks with Moscow that it never truly believed would work. Still, eager to cater to President Trump’s push for a diplomatic solution, Ukraine sent its diplomats into round after round of meetings with American and Russian counterparts, even as the talks yielded scant results.

Now, with Mr. Trump growing increasingly frustrated with Moscow’s refusal to compromise, let alone agree to a cease-fire, Kyiv sees an opening to push for what it has long sought. It wants fewer talks and more weapons to strike Russia, as well as tougher sanctions, to force Moscow to negotiate an end to the war in earnest.

On Tuesday, a high-level Ukrainian delegation will begin a multiday visit in Washington to discuss deals to buy American weapons designed to hit deep inside Russia and shield Ukraine from air attacks. President Volodymyr Zelensky plans to follow with a White House visit on Friday, possibly to finalize agreements. He has been beating the drum for American-made Tomahawk cruise missiles, which would bolster Kyiv’s ability to conduct long-range strikes.

Mr. Trump hinted on Sunday that he might use the possibility of sending the powerful missiles to Ukraine to pressure President Vladimir V. Putin of Russia into laying down arms. “I might say, ‘Look, if this war is not going to get settled, I’m going to send them Tomahawks,’” Mr. Trump said aboard Air Force One.

Experts doubt that the Tomahawks can be a game changer. The missiles are usually launched from ships or submarines, which Ukraine, lacking a navy, does not possess, and the United States has only a limited number of ground launchers available. Mr. Putin has said he does not expect Washington to supply the missiles to Ukraine, while also warning against such an escalation.