Is Western support for Ukraine reaching the end of its rope?

That, after all, was the ultimate outcome of the West's long-running involvement in Afghanistan where, despite spending hundreds of billions of dollars trying to stabilise the country and defeat the Taliban, the US and its allies eventually gave up.

They abandoned the whole enterprise, and, as a result, the Taliban are the country's undisputed masters today.

Kabul withdrawal

Indeed, it could be argued that the Biden administration's chaotic withdrawal from Kabul in 2021, with Kabul airport witnessing scenes not experienced since America's humiliating retreat from Vietnam four decades previously, persuaded Putin that he could achieve his long-term quest to conquer large swathes of neighbouring Ukraine.

And while his military assault on Ukraine has taken far longer than he expected, and caused Russian forces to suffer a series of devastating losses, both in terms of men and equipment, Putin has good reason to believe that, ultimately, his prediction that the West will eventually lose interest in the conflict will be borne out, enabling him to achieve his objectives in Ukraine.

The clearest sign to date that Western support for Ukraine is not open-ended has come in the form of a controversial move by the US Congress to freeze military aid to Ukraine as part of a political row over budget negotiations.

As part of a deal to ensure government funding will continue at least for a further 45 days, Congress has blocked any additional military aid for Ukraine. This decision raises serious questions about the future of US aid for Kyiv.

Just a week after Ukrainian President Volodymyr Zelensky visited Washington to appeal for more funds, the compromise struck in Congress to drop new funding for Ukraine came amid opposition from hardline Republicans.

The move is a bitter blow to US President Joe Biden and his Democratic party, who insist that America has a duty to maintain support for Ukraine, claiming any failure to do so would seriously diminish Washington's global leadership role.

Biden's promises

After Congress agreed on the budget deal, Biden quickly reiterated his support for Ukraine. "I want to assure our American allies, the American people and the people in Ukraine that you can count on our support. We will not walk away," Biden said in an address from the White House.

And Biden urged Republican House Speaker Kevin McCarthy, who played a key role in the negotiations that resulted in the freezing of aid to Kyiv,  to "stop the games", saying he "fully expects" him to secure passage of a separate bill for Ukraine funding in the coming weeks.

Even so, the decision, which reflects the increasingly deep divisions among Republicans over maintaining support for Ukraine, will be seen as proof in the Kremlin that the Western support is waning and that, given time, Putin will be able to succeed in his goal of annexing large areas of Ukrainian territory.

As former US diplomat Brett Bruen remarked after the budget vote, "That ought to worry leaders in Kyiv, and I think in Moscow they're celebrating the signs that our support may be waning."

Nor is it  just in Washington that clear signs of war fatigue among Western leaders are emerging.

In Poland, where the Ukrainian issue is taking centre stage in the country's forthcoming general election, Prime Minister Mateusz Morawiecki said his country is no longer sending arms to Ukraine as a trade dispute between the two states escalates and his populist party faces pressure from the far right in the upcoming national election.

Meanwhile the strong showing by Slovakia's populist former prime minister, Robert Fico, in the country's recent elections has raised questions about its willingness to continue supporting Ukraine following his campaign pledge to end all military aid to Ukraine.

Question marks in Europe

Concerns about the ability of Western countries to maintain their current level of military support to Kyiv have even been raised in the UK, which has been one of Ukraine's staunchest supporters since the start of the conflict, with a senior military source revealing that Britain has run out supplies of defence equipment that it can give to the Ukrainians.

The changing dynamics of the West's support for Ukraine has certainly set alarm bells ringing in the US and Europe, prompting EU leaders to hold an "historic meeting" in Kyiv earlier this week to demonstrate their solidarity with the Ukrainian people.

Josep Borrell, the EU's foreign affairs chief, stressed that, amid political difficulties in the US Congress over financing for Ukraine, the EU's support would be rock solid.

"We are facing an existential threat. Ukrainians are fighting with all their courage and capabilities, and if we want them to succeed, we must give them better weapons, and faster," he said.

Borrell added: "I am hopeful that this decision is not final and that the US will continue to support Ukraine."

So far, Ukraine has sought to play down the implications of Washington's aid freeze saying it was "actively working with its American partners" to ensure new wartime aid.

But with opinion polls, especially in the US, suggesting that public support for Ukraine is declining, this could yet prove to be a watershed moment in the Ukraine conflict, one that ultimately results in Russia achieving its war aims.