US Ambassador: It’s tough to agree on Ukraine's NATO accession timeline while country at war

"Even the Ukrainians themselves will tell you that they need to make further reforms. They've made good progress on a variety of democratic and security sector reforms, but they'll have to continue working in that direction," Smith told CNN Tuesday.

Smith reiterated that Ukraine has already taken positive steps, which led to NATO agreeing to streamline the accession process by removing a key hurdle for Ukraine — the requirement for a Membership Action Plan.

When asked about whether Ukraine's position and the lack of a timeline gives Russia an incentive to continue fighting, Smith emphasized that allies have already committed to Ukraine's future in NATO, as well as to giving the country long-term support.

"(Russian President Vladimir) Putin assumed when he started this war, that he could wait us out that the West would look the other direction and it would ultimately lose interest in Ukraine. And the reality is we're at day 500 of this war, and no one is going anywhere," she said.

According to Smith, the United States is "thrilled" Ukrainian President Volodymyr Zelensky is in attendance for the summit and for the first NATO Ukraine Council, adding, "I think this sends a very strong signal to President Putin."

As reported, NATO Summit is held in Vilnius on July 11-12, in which the President of Ukraine will take part.