The Philippines as a sovereign state is free to enter into contracts with another state and is not bound by United States law, Malacanang said on Thursday.

Presidential Spokesperson Harry Roque was reacting to a Reuters report that the Philippines could breach US sanctions if it would push through with the purchase of grenade launchers from a blacklisted Russian firm.

Roque said the Palace would study the matter.

However, as a former professor of international law and constitutional law, Roque said he did not know how the US could enforce its domestic legislation on a sovereign state, like the Philippines.

"The Philippines is a sovereign state. We have immunity and we are free to enter into contracts as we pleased and we are not bound by any domestic law particularly where the transaction will not occur in US soil," he stressed.

Roque said the government's plan to purchase weapons from Russia’s state-owned Rosoboronexport was an exercise of a function of national defense.

"I do not know how US law could be applicable to a transaction that will be done outside of the United States. The sale will be most likely in Russia; the goods are in Russia and the delivery in the Philippines. So, what is the relevance of US laws?," Roque added

According to Reuters, the Duterte administration had agreed in October last year to a P400-million purchase of 750 RPG-7B rocket-propelled grenade launchers from Rosoboronexport, but the transfer had yet to be completed.

The US has imposed sanctions against any country trading with Russia's defense and intelligence sectors.

Washington has been punishing Russia for its 2014 annexation of Crimea from Ukraine, its support for Syria’s government and alleged meddling in the 2016 US presidential election.

When Duterte assumed office in 2016, he decided to have closer relations with Russia.

He flew to Moscow in May last year, but he had to cut short his visit due to the Marawi siege.

He considered Russian President Vladimir Putin as his close friend. Celerina Monte/DMS