"Of course, there's a lot of criticism, but I think some of it is also true," Kallas told the Doha Forum, an annual diplomatic conference in Qatar's capital, in response to a question about the US strategy.
The "US is still our biggest ally... I think we haven't always seen eye to eye on different topics, but I think the overall principle is still there. We are the biggest allies, and we should stick together."
Washington's new National Security Strategy, published early Friday, took aim at Europe, calling it over-regulated, lacking in "self-confidence" and facing "civilizational erasure" due to immigration.
The document puts into writing the offensive launched months ago by US President Donald Trump's administration against Europe, which the US has accused of taking advantage of American generosity, a radical departure from previous US policy.
"Europe has been underestimating its own power. Towards Russia, for example... we should be more self-confident," Kallas said.
Ukrainian and US officials will hold a third straight day of talks in Miami on Saturday, in discussions aimed at ending over three years of war with Russia.
Washington's plan involves Ukraine surrendering land that Russia has not been able to win on the battlefield in return for security promises that fall short of Kyiv's aspirations to join NATO.
"Putting limitations and stress on Ukraine actually does not bring us long-lasting peace," Kallas told the Doha Forum.
"If aggression is rewarded, we will see it happen again, and not only in Ukraine or Gaza, but all around the world," she added.
