Trump keeps threatening to punish Putin. Here's what's holding him back

U.S. President Donald Trump has repeatedly said he will punish Russia and President Vladimir Putin if Moscow doesn't come to the table and agree to peace talks or a ceasefire with Ukraine.

Russia has shown no signs of intending to do either, instead continuing and increasing its attacks on Ukraine as it looks to consolidate gains on the battlefield.

And still, Trump is holding off on releasing a big bazooka of extra sanctions and economic punishment that could hurt an already weakened Russia.

The reason for the standstill is strategic and goes beyond Russia, according to analysts, who warn the longer Trump holds off, the more he's undermining his and the U.S.' position.

"The Russian budget is actually under a lot of pressure... so if there were to be any more significant sanctions targeting Russian oil trade from the U.S. — which they've talked about but not done — that would put the budget under greater pressure. It hasn't happened," Chris Weafer, the chief executive of Moscow-based Macro-Advisory, told CNBC Monday.

There were two significant factors behind Trump's reticence, Weafer said: the president's desire to be seen as a peace-broker, and concerns over pushing Russia deeper into China's orbit.

"Trump still thinks he can bring both sides to the table, that he could broker a peace deal, and that he can take credit for moving the conflict towards peace. And bearing in mind that the announcement on the Nobel Peace Prize will come in early October, it's a factor, because we know the character of the of the individual," he told CNBC's "Squawk Box Europe."

"The second reason ... is there is a sense that if Russia is defeated, if Russia is completely isolated by the West, and there's no way back in terms of engaging with the U.S. and Europe, then it has no choice but to go even further all-in with China, and that potentially then would strengthen China's position."

Bringing Russia and Beijing closer together would mean that the latter had "almost unlimited" access to energy resources, industrial materials and to the Arctic, the analyst said, noting that this could effectively block the U.S. from Russian-controlled parts of the Arctic.

It would also allow China greater access to Russian military technology, such as stealth submarines, and further opportunities in space exploration.

Officials in Washington were concerned about that, Weafer noted, adding, "they don't want Russia to be essentially a more formal subsidiary of China. They want it to be more in the middle with engagement in the West. I think that's one reason why they're treading carefully for now."

CNBC has contacted the White House for further comment on its strategy toward Moscow and is awaiting a response.

Ukraine, meanwhile, has watched as Trump has let self-imposed deadlines to act against Russia pass, with Kyiv left crestfallen at perceived missed opportunities to pressure Putin into a ceasefire.

"Ukrainians had hoped that Trump's August 8 deadline for Putin to accept a cease-fire would provide more constant air defense," John Herbst, a former U.S. ambassador to Ukraine and the head of the Atlantic Council's Eurasia Center, said in analysis in August.

Yet, they were disappointed when Trump let Putin cross his August 8 deadline to end the fighting without consequences. "Instead, Trump focused on summitry with Putin, which has yet to yield Russian flexibility," Herbst wrote.

"Now they are gritting their teeth and, with many of their European partners, waiting for White House officials to realize that Russia is playing them — and to take the strong measures that Trump promised if Russia continued its war on Ukraine," he added.

Beijing and Moscow's leaders were seen to be putting on a display of bonhomie at the 25th Shanghai Cooperation Organization summit on Monday. The SCO is being attended by 20 foreign leaders, including Putin and Indian Prime Minister Narendra Modi.

Against a backdrop of war in Ukraine, Trump's tariffs and continuing oil trade, the major economies of China, Russia and India have deepened their economic and political ties while their respective relations with the West have frayed.

Chinese President Xi Jinping on Monday urged his fellow leaders attending the summit to strengthen their cooperation, and called on them to reject what he called a "Cold War mentality."

Meanwhile, Putin told the SCO that his meeting with Trump in August had opened a path to finding a way to resolving the Ukrainian "crisis," as he described the more than three-year war. Yet he thanked Russia's Asian allies for their support throughout the war.

"We value the efforts and propositions to solve the Ukrainian crisis of China, India and other strategic partners of ours. The mutual understanding that was reached at a recent Russia-U.S. summit in Alaska heads the same direction, I hope. It paves the way to peace in Ukraine, I hope."

Summits like the SCO were creating a new political and socio-economic ecosystem that could replace the "outdated" Euro-Atlantic-centered power model, Putin said.

This new system "would take into account the interests of a maximum number of countries and would be truly balanced," meaning "a system in which one group of countries would not ensure its security at the expense of the others."