Shehzad Chaudhry, a retired Pakistani military air vice marshal and former diplomat, said "a new relationship is very much on the cards" between the former foes.

“With the Russians and the Pakistanis, it’s a big strategic change," he added.

Kamal Alam, a Pakistan and Middle East expert at Royal United Services Institute, a London think tank, said the Trump administration’s approach was viewed as a source of frustration in Islamabad.

Alam added that Pakistan's powerful military appeared to have "had enough of America’s blackmailing, threats and blockage of sales."

Cricketer-turned-politician Imran Khan in Pakistan's Parliament on Aug. 13. Pakistan Press Information Department Handout / via AFP - Getty Images

While Russia-Pakistan strategic dialogue, training and military sales began in earnest around a decade ago, the Trump administration’s apparent antipathy along with the victory of cricket-icon-turned-anti-corruption crusader Imran Khan in last month's election appear to have provided an opportunity for Moscow to significantly ramp up its influence in the country. Khan took office as prime minister on Saturday.

Russia was among the first to send top military brass to Pakistan after Khan's election win, with Deputy Defense Minister Alexander Fomin being dispatched to discuss security cooperation.

Russia also beat the U.S. in terms of congratulating Khan, with the country’s ambassador arriving at the prime minister-elect’s residence to give his regards in person.

“This is a mixture of timing, exhaustion of patience with Washington and a culmination of what began earlier with [Russian] training, military sales and intel sharing,” Alam said.

The blossoming of Pakistan-Russia relations has also partially been a response to the Trump administration’s increasing closeness with Prime Minister Narendra Modi in arch-rival India. India has traditionally been Russia’s main South Asian partner.

Indian Prime Minister Narendra Modi meets with Russian President Vladimir Putin during a summit in Johannesburg, South Africa, on July 26. Alexei Nikolsky / AP

“With the Indians and the U.S. getting closer, the Russians have found space to break away ... and begin to exercise a little more freedom with countries like Pakistan,” said Chaudhry, the retired air marshal who previously served as Pakistani ambassador to Sri Lanka.

Chaudhry believes the perceived U.S. retreat is creating space for other countries including China, Iran and Turkey to also gain influence in the region.

Such changes could have a big effect on the 17-year-old war in Afghanistan. Trump has grown increasingly frustrated with the conflict, prompting U.S. peace talks with the Taliban.

“Afghanistan will be influenced by these powers as well. It’s not just about a helicopter here or a tank there," Chaudhry said. "This new arrangement, not just between Pakistan and Russia, but this entire bloc of countries, has got strategic possibilities, because the center of gravity, globally and economically is shifting east."

But Siddiqui, the ambassador, insisted it was too early to write off the relationship.

"Its importance has been proven over decades," he said. "We are working on fixing it."