U.S. President Joe Biden and his French counterpart Emmanuel Macron on Thursday agreed to continue to support Ukraine's defense against Russia's aggression, while affirming the importance of maintaining peace over Taiwan, a self-ruled democratic island facing pressure from an increasingly assertive China.

In a joint statement issued after their meeting in Washington, the two leaders also strongly condemned North Korea's barrage of missile tests, saying they pose a "threat" to the region.

Biden is hosting Macron for the first state visit by a foreign leader under his administration, and following a diplomatic spat last year over a deal among the United States, Australia and Britain that will help Canberra acquire nuclear-powered submarines instead of diesel ones from France.

Combined photo shows U.S. President Joe Biden (L) and French President Emmanuel Macron. (Getty/Kyodo)

The two leaders apparently sought to display the strength of the bilateral relationship, with Biden touting France as the United States' "oldest ally" and "unwavering partner in freedom's cause" during an arrival ceremony at the White House.

In the joint statement, the two allies of the North Atlantic Treaty Organization pledged security, humanitarian and economic assistance to Ukraine for "as long as it takes," including stepping up the delivery of air defense systems and equipment needed to repair Ukraine's energy grid as winter arrives.

As two nations of the Indo-Pacific, they said they intend to increase "practical" cooperation in the region on maritime security and will continue to "coordinate on our concerns regarding China's challenge to the rules-based international order, including respect for human rights."

The two presidents agreed on "the importance of maintaining peace and stability across the Taiwan Strait," their statement said.

Taiwan has been drawing attention as a potential military flashpoint in the Indo-Pacific, with China regarding the island as a renegade province to be reunified with the mainland, by force if necessary. China and Taiwan have been governed separately since they split in 1949 due to a civil war.

When Macron met Biden in October last year in Rome, Taiwan was not mentioned in a post-meeting statement. Including the Taiwan issue in their latest statement may signal their deepening concerns over the situation.

Tensions over Taiwan have heightened this year between the United States and China, as Beijing increased its military activity in response to a visit to the island in August by U.S. House of Representatives Speaker Nancy Pelosi, the third-highest-ranking U.S. official.

France is a key player in the Indo-Pacific, having overseas territories and a permanent military presence in the region. The country also sends warships into the South China Sea, where Beijing has been aggressively pushing its territorial claims.

But it has also pursued a "third way" between Washington and Beijing, showing caution about getting increasingly aligned with the hawkish U.S. approach to China.

In their joint statement, the United States and France expressed their opposition to a U.N. treaty banning nuclear weapons, which entered into force in January last year with no nuclear powers supporting it.

The two countries reaffirmed that nuclear deterrence remains essential for national security, while criticizing the Treaty on the Prohibition of Nuclear Weapons because it "does not reflect the increasingly challenging international security environment."

On the economic front, Biden and Macron appeared to be moving toward easing tensions over a new U.S. law that includes electric vehicle tax credits feared to put non-American automakers at a disadvantage.

The Inflation Reduction Act, signed into law by Biden in August and touted as facilitating "historic" investments in green technology and clean energy, requires final assembly of EVs to occur in North America to qualify for the tax credits. Countries such as Japan and South Korea have also expressed concerns over the U.S. measure.

Biden told a joint press conference with Macron after their meeting that there are "tweaks" the U.S. side can make to address the concerns, without elaborating.

"That is something that is a matter to be worked out," he said, noting the law was "never intended to exclude folks who were cooperating with us."