As the first anniversary of the Russian invasion of Ukraine approaches, U.S. officials are telling the Ukrainian leadership that they are facing a turning point to change the trajectory of the war, The Washington Post reports.

As the paper notes, they are increasing pressure on Kyiv to make significant gains on the battlefield, while arms and aid shipments from the United States and its allies are increasing.

Despite promises to support Ukraine "as long as it takes," Biden officials say recent aid packages from Congress and America's allies represent Kyiv's best chance to decisively change the course of the war.

Several officials noted the strong bipartisan support that accompanied each aid package to Ukraine, adding that Congress gave the White House more than it asked for. They acknowledged, however, that it was done under the leadership of the Democrat-led House and Senate.

"We will continue to try to impress upon them that we can't do anything and everything forever," said a senior source in the Biden administration, referring to the Ukrainian leaders. The anonymous source added that the administration is very firmly of the view that it will be difficult to continue getting the same level of security and economic assistance from Congress.

"'As long as it takes’ pertains to the amount of conflict," he added, "It doesn’t pertain to the amount of assistance."

A senior source also said that the Biden administration will continue to request as much funding as it believes Ukraine needs, as it has done throughout the war. He stressed, however, that there is no guarantee that Congress will approve these requests. Republicans took control of the House of Representatives in January, and while many key lawmakers have expressed support for continued funding, the party also has to contend with an extreme right-wing flank that has expressed skepticism or opposition to additional funding for the war.

The war has become a slow routine in eastern Ukraine in recent months, with neither side gaining the upper hand. Biden officials believe the turning point will come this spring, when Russia is expected to launch an offensive and Ukraine will go on a counteroffensive in an attempt to regain lost territory.

The critical nature of the next few months has already been brought to Kiev's attention in sharp terms by senior Biden representatives, including Deputy National Security Adviser John Feiner, Undersecretary of State Wendy Sherman and Deputy Defense Secretary Colin Kahl, all of whom visited Ukraine in January, the paper wrote.