The menacing 40-mile-long Russian military vehicle convoy bearing down on Kyiv appears to have stalled

• A 40-mile long Russian military convoy apparently on its way to Kyiv seems to have stalled.
• A senior US defense official said it could be logistics problems, but Russia may also be "regrouping, rethinking, reevaluating" its invasion.

A large 40-mile-long convoy of Russian military vehicles appears to have stalled on its way to Kyiv, the capital of Ukraine and a key objective as more and more Russian forces move into the country to support Russian President Vladimir Putin's invasion.

Russia's invasion of Ukraine has suffered a number of setbacks, and the Russian advance has slowed in the face of not only substantial Ukrainian resistance but also logistics and supply problems.

Some invading Russian forces are "literally out of gas" and are "having problems feeding their troops," according to a senior US defense official who briefed reporters on Tuesday.

The US has observed that the Russian forces "face greater resistance than they thought, that they have experienced fuel and logistics challenges — and we've been talking about that for a few days, it remains to be the case today," the official said.

"In many cases," the official continued, "what we're seeing are columns that are literally out of gas, and as I said earlier, now they're starting to run out of food for their troops."

They explained that "the main advance on Kyiv basically remains where it was yesterday, so no appreciable movement from the Russians coming down from the north."

The large convoy is stalled about 18 miles north of Kyiv and includes tanks, armored vehicles, artillery and supplies, according to a Tuesday NPR report.

Although the official highlighted Russia's logistics problems, they noted that part of the reason for the stall could be that Russia has decided to pause its operations, "that they are possibly regrouping, rethinking, reevaluating."

In another background briefing Wednesday, a senior US defense official said that the Russians "continue to be, to be bedeviled by these logistical and sustainment issues" and that "basically they remain stalled outside the city" of Kyiv, according to reporters on the call.

"We believe that the convoy is stalled," they said.

"It is a long convoy, so I can't be perfectly predictive on every mile of that, whether they're moving or not, but they are not moving at any rate that would lead one to believe that they've solved their problems."

The official said that while the US has limited visibility on the convoy, the movement of these assets toward the Ukrainian capital was "clearly an effort" to reinvigorate Russia's blunted assault on Kyiv, which Russia has failed to take despite expectations the city would fall in days.

Commercial satellite images recently provided by Maxar Technologies showed smoke and fire rising from buildings near the roadway where the convoy was moving — but it was not immediately clear what the damage was caused by.

The defense official who spoke to reporters on Tuesday said the US believes about 80% of the estimated 190,000 Russian troops that were amassed along Ukraine's border are now in the country. And while Russia has stumbled in the early days of this fight, it is expected to adjust course.

"They will regroup, they will adjust, they will change their tactics," the official said. The following day, an official said that "we believe the Russians will learn from these missteps and stumbles."