Ukraine will eventually join NATO as support from its member countries remains "rock solid," U.S. Secretary of State Antony Blinken said Thursday.

"Ukraine will become a member of NATO. Our purpose at the summit is to help build a bridge to that membership," Blinken told reporters in Brussels.

Blinken's remarks came after a meeting with Ukrainian Foreign Minister Dmytro Kuleba at the NATO Foreign Ministers Meeting.

"Of course, we believe that Ukraine deserves to be a member of NATO and that this should happen sooner rather than later," Kuleba said. 

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Both men discussed Ukraine's war with Russia and ways to bolster Ukraine's energy sector amid attacks from Moscow. 

Ukraine's potential membership in the 32-member alliance is seen as partly why Russia invaded the country. Sweden officially joined NATO on March 7. 

In response to his remarks, Sen. J.D. Vance, R-Ohio, called Blinken's statement "irresponsible."

"Ukraine should not join NATO, and to invite them during a war is to invite our nation into war," he posted on X. "Do you want American ground troops in Ukraine? If not, we must push back against the idea that Ukraine should join NATO."

The alliance is debating a plan to provide more military assistance to Ukraine as Russia asserts more control on the battlefield. 

"We strongly believe that support to Ukraine should be less dependent on short-term, voluntary offers and more dependent on long-term NATO commitments," NATO Secretary-General Jens Stoltenberg said before chairing a meeting of the alliance’s foreign ministers in Brussels.

Blinken the Ukraine's allies will make sure it has what it needs to counter Moscow's aggression. 

Meanwhile, additional American assistance has been held up by House Republicans.

Western pledges of support to Ukraine have been marred by broken promises. A European vow to provide 1 million rounds of ammunition fell woefully short, and financial aid meant for Ukraine’s war-stricken economy was delayed by political infighting in Europe and is still blocked in the U.S.

The Associated Press contributed to this report.