A national security expert noted on Monday that there are a few important things President Donald Trump hasn't said ahead of his meeting with Russian President Vladimir Putin.

David Sanger, CNN national security analyst, said on "The Arena" with anchor Kasie Hunt that Trump has thus far said Ukraine may need to give up some of its land to end the war with Russia. While that offer is problematic on its face, Sanger said the unspoken parts of the deal are harder to stomach.

"It's what you didn't hear that disturbs me more, and I suspect disturbs the Ukrainians and our European allies," Sanger said.

"He never once mentioned security guarantees for the Ukrainians, so that Russia doesn't just take a pause, or a couple of years to re-arm and then seek again to take over the entire country," he continued.

"He didn't say anything about a commitment to arm Ukraine to deter a future attack or future contributing intelligence," Sanger added. "The Europeans stressed all of those over the land issues in their statements over the weekend."

Trump and Putin are scheduled to meet this week in Alaska, a former Russian territory that the U.S. purchased in 1867.

Sanger also noted that the location of the Trump-Putin summit was significant. Not only will it be in a former Soviet territory, but it will also occur in a NATO country.

Sanger said the meeting may help Putin project an image of "acceptance" on the global stage.

Watch the entire segment below or by clicking here.