Ukrainian President Volodymyr Zelensky is not seeking the deployment of United States troops to fight on Ukrainian soil, White House National Security Communications Adviser John Kirby said Tuesday.

Zelensky, Kirby argued, is urgently requesting additional security assistance as Ukraine's munition supplies are depleting in light of the Russian offensive.

"There's not going to be US troops on the ground fighting inside Ukraine... President Zelensky isn't asking for that, he's just asking for the tools and capabilities," Kirby claimed.

He continued by stressing that the Ukrainian leader and his troops were determined to defend their country but required essential resources to do so effectively.

Kirby went on to highlight the critical need for swift action, expressing concern over the delay in Congress approving additional funding for Ukraine's security assistance. According to Kirby, this delay is already having detrimental effects on Ukrainian soldiers on the front lines.

As Russia continues to push westward out of the Donbass region, Ukraine's defensive lines are reportedly shifting in the "wrong direction," raising alarms about the urgency of providing necessary support to Ukrainian forces.

The White House, at this time, is grappling with the geopolitical implications of the Congressional delays, as Kirby noted, "Ukraine's defensive lines are starting to shift in the wrong direction because the Russians continue to push west out of the Donbass."

Ukraine in collapse?

NewsWeek reported on Thursday, citing military sources, that the recent capture of Avdiivka has been followed by the continuous expansion of Russian control along the frontlines.

According to the source, Ukrainian forces are "both outmanned and outgunned along the front." The recent fall of Avdiivka was in part blamed on ammunition shortages.

Since then, Russia's expansion has been "incremental" and will likely increase in the short term as long as aid remains stalled in the West. 

According to the arms-maker-funded Institute for the Study of War, the victory in the battle of Avdiivka has opened new avenues for land control in surrounding areas, and Russian forces are working rapidly to increase their presence along the frontlines before Ukrainian forces rebuild a more cohesive defense line. 

Other think tanks found that Russian troops have expanded to other parts of Donetsk, including west of Bakhmut and eastern parts of Ivanivske.

"Avdiivka was a pyrrhic victory but a victory nonetheless. The ground behind it is flatter and the breaching of this stronghold calls into question Ukraine's overall strategy amid the hold-up in US Congress," Zev Faintuch, the senior intelligence analyst at security firm Global Guardian, told NewsWeek.

"If the [US] aid bill isn't passed soon, there will be more Avdiivkas as Russia tries to seize the opportunity to cement its gains in Donetsk," Faintuch told Newsweek.

How strong are Ukraine's defense lines?

"Behind Avdiivka, Ukraine has some defenses, but it is not a strong line," Military analyst Mike Kofman told the War on the Rocks podcast.

"The Russian military may run out of momentum, but on the other hand if they are able to fully sustain these offensive pushes over the coming year, then eventually they may find more and more open terrain," which could lead to a "potentially slippery slope."

Earlier this week, Zelensky admitted that an estimated 31,000 Ukrainian troops had been killed in two years of war. However, estimates vary among observers. 

Read more: Ukraine ammo shortage aiding Putin: Zelensky

"Zelensky hasn't amended his stated political goals of total territorial liberation," said Faintuch. "It's a hard sell to now tell the young folks they need to go make sacrifices in meat grinders like Bakhmut and Avdiivka to preserve the status quo, as opposed to making sacrifices for a tangible total victory."

"Ukraine is both outmanned and outgunned along the front and Zelensky is in a bind politically," he said. "Ukraine needs to adopt an active defense strategy. It can trade space for time, seeing as Ukraine is massive territorially. Russia has only really been able to advance in areas where it can amass superiority in artillery fires and manpower."

With the upcoming provision of fighter jets, observers anticipate the scale of power to be altered.