KUALA LUMPUR, Malaysia (AP) -- U.S. Secretary of State Marco Rubio and his Russian counterpart will meet Thursday in Malaysia for what could be a testy conversation as tensions between the countries rise over Moscow's increasing attacks on Ukraine and questions about whether Russia's leader is serious about a peace deal.

Rubio and Foreign Minister Sergey Lavrov are to see each other in Kuala Lumpur, where both men are attending the annual Association of Southeast Asian Nations Regional Forum, which brings together all 10 ASEAN members and their most important diplomatic partners, including Russia, China, Japan, South Korea, the Europeans and the U.S.

The meeting will be their second face-to-face encounter since Rubio took office, although they have spoken by phone several times. Their first meeting came in February in Riyadh, Saudi Arabia, as the Trump administration sought to test both Russia and Ukraine on their willingness to make peace.

This one is set to take place shortly after the U.S. resumed some shipments of defensive weapons to Ukraine following a pause -- ostensibly for the Pentagon to review domestic munitions stocks -- that was cheered in Moscow.

The resumption comes as Russia fires escalating air attacks on Ukraine and as U.S. President Donald Trump has become increasingly frustrated with Russian President Vladimir Putin.

"Putin is not, he's not treating human beings right," Trump said during a Cabinet meeting Tuesday, explaining the pause's reversal. "It's killing too many people. So we're sending some defensive weapons to Ukraine, and I've approved that."

Rubio was also seeing other foreign ministers, including many whose countries face tariffs set to be imposed on Aug. 1. The tariff threat could overshadow the top diplomat's first official trip to Asia, just as the U.S. seeks to boost relations with Indo-Pacific nations to counter China's growing influence in the region.

Rubio sought to assuage concerns as he held group talks with ASEAN foreign ministers.

"The Indo Pacific, the region, remains a focal point of U.S. foreign policy," he told them. "When I hear in the news that perhaps the United States or the world might be distracted by events in other parts of the planet, I would say distraction is impossible, because it is our strong view and the reality that this century and the story of next 50 years will largely be written here in this region."

"These are relationships and partnerships that we intend to continue to build on without seeking the approval or the permission of any other actor in the region of the world," he said in an apparent reference to China.

Trump notified several countries on Monday and Wednesday that they will face higher tariffs if they don't make trade deals with the U.S. Among them are eight of ASEAN's 10 members.

U.S. State Department officials said tariffs and trade won't be Rubio's focus during the meetings, which Trump's Republican administration hopes will prioritize maritime safety and security in the South China Sea, where China has become increasingly aggressive toward its small neighbors, as well as combating transnational crime.

But Rubio may be hard-pressed to avoid the tariff issue that has vexed some of Washington's closest allies and partners in Asia, including Japan and South Korea and most members of ASEAN, which Trump says would face 25% tariffs if there's no deal.

Malaysian Prime Minister Anwar Ibrahim has warned that global trade is being weaponized to coerce weaker nations. Speaking at an ASEAN foreign ministers' meeting on Wednesday, Anwar urged the bloc to strengthen regional trade and reduce reliance on external powers.

Rubio's "talking points on the China threat will not resonate with officials whose industries are being battered by 30-40% tariffs," said Danny Russel, vice president of the Asia Society Policy Institute and a former assistant secretary of state for East Asia and the Pacific during the Obama administration.

When Anwar said "ASEAN will approach challenges 'as a united bloc' -- he wasn't talking about Chinese coercion but about U.S. tariffs," Russel noted.

Among ASEAN states, Trump has so far announced tariffs on almost all of the 10 members of the bloc, which would face a 25% tariff that could specifically hit its electronics and electrical product exports to the United States.

Trade Minister Zafrul Aziz said Wednesday that while Malaysia is ready to resume tariff negotiations, it wouldn't cross its red lines, including U.S. requests for changes to government procurement, halal certification, medical standards and digital taxes.

Trump sent tariff letters to two more ASEAN members Wednesday: Brunei, whose imports would be taxed at 25%, and the Philippines at 20%. Others hit this week include Cambodia at 36%, Indonesia at 32%, Laos at 40%, Malaysia at 25%, Myanmar at 40% and Thailand at 36%.

Vietnam recently agreed to a trade deal for a 20% tariffs on its imports, while Singapore still faces a 10% tariff that was imposed in April. The Trump administration has courted most Southeast Asian nations in a bid to blunt or at least temper China's push to dominate the region.

In Kuala Lumpur, Rubio also will likely come face-to-face with China's foreign minister during his brief visit of roughly 36 hours.

Russel noted that Chinese Foreign Minister Wang Yi is a veteran of such gatherings and "fluent in ASEAN principles and conventions," while Rubio "is a rookie trying to sell an 'America First' message to a deeply skeptical audience."

Issues with China, including on trade, human rights, the militarization of the South China Sea and China's support for Russia in Ukraine, remain substantial.

U.S. officials continue to accuse China of resupplying and revamping Russia's military industrial sector, allowing it to produce additional weapons that it can use to attack Ukraine.

Earlier on Thursday, Rubio signed a memorandum on civilian nuclear energy memorandum with Malaysia's foreign minister, which will pave the way for negotiations on a more formal nuclear cooperation deal, known as a 123 agreement after the section of U.S. law that allows them.

Such agreements allow the U.S. and U.S. companies to work with and invest in civilian energy nuclear programs in other countries under strict supervision.

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Eileen Ng contributed to this report from Kuala Lumpur, Malaysia.