The ongoing saga of US whistleblower Edward Snowden is just a pretext of the cooling relations between Russia and the United States, a Russian expert said Monday.

While the Snowden case is just an excuse, a lack of real progress on core bilateral issues is among underlying reasons behind US President Barack Obama's decision to cancel a planned summit meeting with his Russian counterpart Vladimir Putin, said Feodor Voitolovsky, a scholar at Russian Academy of Science.

"I don't think we need to take Snowden's situation seriously in the context of Russia- US relations. Of course, this is one of the issues but a small one," Voitolovsky told Xinhua.

Though Obama argued for a "reassessment and calibration" of its relationship with Moscow following Russia's move to grant the American intelligence leaker a temporary asylum, normal contacts and dialogues between the two countries did not stop, as a "2+2" meeting was held as scheduled in Washington, he added.

The high-level meeting covers a wide range of principal bilateral topics including the ballistic missile defense, but the two sides remain divergent on various issues, Voitolovsky said.

Until the upcoming Group of Twenty (G20) summit, there's not enough time to level these differences and find compromises, and few agreements have been prepared for signature by the two presidents.

"I guess Obama and Putin will have some sort of dialogue on the sidelines of G20, but they don't have enough materials for separate bilateral meetings. They need to build more positive agenda which requires more time to fulfill," Voitolovsky added.

Meanwhile, the expert foresaw no breakthrough of Russia-US ties, citing reasons such as loose economic ties and unbalance of interdependency.

"The lack of economic motivation buries many aspects of political relations, breaks development of dialogues on many problems not directly related to military security. It may take years until the solid ground would be formed for a qualitatively different dialogue between the two countries," he said.

Indeed, Washington's approach to the Russia-US relationship is very pragmatic, Voitolovsky said. "When the US interests coincide with a chance to push forward bilateral ties, Washington makes it. When there is no clear benefits for the US, Washington simply ignores Russia, and any other country," he said.

According to the expert, anti-missile defense is less a military threat to Moscow than a political barrier between Russia and the European Union. "Let's be realistic: missile defense is a dead-end problem in their relations."

The warming of the Russia-US ties will be possible after the next US Congressional election, the expert estimated, adding the opportunity might appear depending on the composition of the Congress.