MANILA - (UPDATE) Malacañang on Thursday scoffed at the idea of the United States imposing sanctions on the Philippines if Manila pushes through with its planned purchase of arms from Russia.

Under a law that US President Donald Trump signed in August, any country trading with Russia’s defense and intelligence sectors will face sanctions.

The law is designed to punish Russia for its 2014 annexation of Crimea from Ukraine, its support for Syria's government and alleged meddling in the 2016 US presidential election.

Presidential Spokesperson Harry Roque, an international law professor, said the US law on sanctions is an example of “transnational” and “extraterritorial” legislation by the world’s largest economy which he noted could be in violation of Philippine sovereignty.

He said while the administration will still study the matter, he believes the planned purchase of grenade launchers from blacklisted Russian state-owned firm Rosoboronexport is a sovereign decision of the Philippines.

“In the exercise of a function of national defense, we have absolute immunity as a sovereign state. I don’t know how a US law could be applicable to a transaction that will be done outside the US,” Roque said in a press briefing.

“The sale will be in Russia; the goods are in Russia; and the delivery will be in the Philippines.”

A senior Philippine general familiar with the deal said Manila had agreed in October last year to a P400 million ($7.48 million) purchase of 750 RPG-7B rocket-propelled grenade launchers from Russia's state-owned Rosoboronexport, but the transfer had yet to be completed.

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Russia has donated assault rifles and trucks to the Philippines but the grenade launchers would be Manila's first purchase of Russian weapons. The Philippines has long relied on the United States as its main source of military hardware and support.

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If it goes ahead, the deal could add strain to a nearly 70-year-old security alliance that Washington has described as "ironclad," despite Philippine President Rodrigo Duterte's disdain for the relationship with the former colonial power.

The Armed Forces of the Philippines meanwhile said they have yet to receive any formal advise on whether Manila will indeed receive sanctions from the US if it proceeds with the Moscow deal.

“Wala pa malinaw na information tungkol dyan,” AFP spokesperson Col. Edgar Arevalo said.

“Wala pa kaming natatanggap na abiso na magkaroon ng ganong violation,” he added.

(There is no clear information on that yet. We haven't received any advice that there will be a violation.)

Duterte wants closer ties with China and Russia and has ordered the army and police to engage with countries which do not impose conditions on weapons sales.

Some US legislators campaigned to block sales of 26,000 assault rifles to the Philippines in May 2017 because of human rights concerns over an anti-narcotics campaign that has killed thousands of Filipinos.

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Duterte scrapped that deal, as well as the purchase of $233 million worth of Canadian helicopters, over concerns by the sellers about how they would be used.

A US State Department official said foreign governments and private sector entities had been put on notice that "significant transactions with any of the 39 listed entities will result in sanctions." Rosoboronexport was blacklisted in April.

American allies who buy weapons and equipment from Russia, the world's second-largest arms exporter, would also be penalized and could see the transfer of those arms disrupted.

-with a report from Ron Gagalac, ABS-CBN News and Reuters