Russian President Vladimir Putin will visit Hanoi this week, multiple officials said, highlighting Communist-ruled Vietnam's loyalty to Russia and triggering a U.S. rebuke.

The visit follows Hanoi avoiding a Ukraine peace summit in Switzerland last weekend, while sending its deputy foreign minister to a BRICS meeting in Russia earlier last week.

Putin, who was sworn in for a fifth time just over a month ago, is expected to meet Vietnam's new president, To Lam, and other leaders during the two-day visit to Hanoi on Wednesday and Thursday, officials said.

The United States, which upgraded relations with Hanoi last year and is Vietnam's top trading partner, reacted harshly.

"No country should give Putin a platform to promote his war of aggression and otherwise allow him to normalise his atrocities," a spokesperson for the U.S. embassy in Hanoi told Reuters when asked about the impact of the visit on ties with the United States.

"If he is able to travel freely, it could normalize Russia's blatant violations of international law," the spokesperson added, referring to the invasion of Ukraine that Putin launched in February 2022.

Vietnam's foreign ministry did not reply to a request for comment.

The Hague-based International Criminal Court (ICC) issued in March 2023 an arrest warrant for the Russian president over alleged war crimes in Ukraine. Vietnam, Russia and the U.S. are not members of the ICC.

The European Union, another key economic partner for Vietnam, did not comment ahead of the visit, but it expressed dissatisfaction last month over Hanoi's decision to delay a meeting with the EU envoy on Russian sanctions - a delay that officials linked to preparations for Putin's visit.

From Hanoi's perspective, the visit is meant "to demonstrate that Vietnam pursues a balanced foreign policy that does not favour any of the major powers," said Ian Storey, senior fellow at the Singapore-based ISEAS-Yusof Ishak Institute, after the country hosted Joe Biden and Xi Jinping in recent months.