Russian President Vladimir Putin will oversee the signing of a USD 5 billion deal this week to supply Delhi with S-400 air defence systems, a top Kremlin aide said on Tuesday ahead of Putin’s trip to India.

“The president is leaving for India on October 4,” Putin’s top foreign policy aide Yury Ushakov told reporters.

“The key feature of this visit will be the signing of the agreement to deliver S-400 air defence systems,” he said. “The value of the contract will be more than USD 5 billion.”

Russian President Vladimir Putin will visit India on 4-5 October for the 19th India-Russia annual bilateral summit, it was officially announced on Friday.

Moscow has been negotiating to sell the S-400 long-range surface-to-air missiles to India for months.

The sale has irked India’s defence partner Washington, which has wanted to wean India off Russian technology, and a senior Pentagon official said in August that sanctions against India would come under consideration if its purchase goes through.

Earlier last week, Russia had said that India will make a “sovereign decision” on Russian defence purchases.

Read | India will make ‘sovereign decision’ on defence purchases: Russia

India has signalled it will ask Washington for a special waiver from sanctions, though a US official last week said there is no guarantee it would do so.

The Countering America’s Adversaries Through Sanctions Act (CAATSA) passed last year by the US Congress imposes sanctions on some Russian companies as well as on their customers and this could impact India’s defence deals with Russia.

India will need exemptions from CAATSA to buy the S-400 Triumf missile defence system as well as frigates and helicopters.

Putin is scheduled to hold the summit with Prime Minister Narendra Modi on 5 October. He will also meet President Ram Nath Kovind and other Indian leaders.

A number of agreements are expected to be signed between the two countries following the summit.

The two countries are also looking at the possibility of inking the much-anticipated S-400 Triumph missile defence system deal which could attract punitive action by the US under the CAATSA.

The agenda of talks between Modi and Putin includes key aspects of special privileged partnership between their two countries.

The two leaders are expected to review global developments, including the situation in Afghanistan and Syria, and implications of the US decision to pull out of the Iranian nuclear deal.

They will also take stock of bilateral ties especially against the backdrop of the growing impression that Russia was reaching out to Pakistan, much to the discomfort of India.

Apart from participating in the summit, the two leaders will also attend a meeting of the India-Russia business forum.

The last India-Russia summit was held in June 2017 when Modi visited St Petersburg.

(With agency inputs)