The heads of the American and British foreign intelligence agencies said in a joint essay published Saturday that ongoing support for Ukraine in its conflict with Russia is essential.

They pledged to enhance cooperation between their agencies and address other global challenges.

CIA Director William Burns and Richard Moore, head of Britain’s MI6 secret intelligence service, wrote the opinion piece in the Financial Times newspaper.

This marks the first time the leaders of the two agencies have co-written an essay.

The spy chiefs highlighted that their partnership is a cornerstone of the “special relationship” between the U.S. and Britain.

They noted that their agencies have collaborated for 75 years and are united in opposing Russia’s aggression against Ukraine.

“Staying the course in Ukraine is more vital than ever,” they wrote.

Russian President Vladimir Putin, they said, “will not succeed in extinguishing Ukraine’s sovereignty and independence.”

They committed to continuing support for Ukrainian intelligence.

Russian forces are making slow progress in eastern Ukraine, while Ukrainian troops continue their activities in Russia’s Kursk region.

Kyiv has been seeking additional air defense support from the U.S. and its allies.

The spy chiefs also addressed Russian intelligence operations, accusing them of sabotage and disinformation across Europe.

Russia has denied those allegations.

Burns and Moore said their agencies have reorganized to confront a growing challenge from China, which they described as the principal intelligence and geopolitical concern of the 21st century.

They also emphasized their efforts to use intelligence to promote restraint and de-escalation in the Middle East, including working toward a cease-fire in the Israel-Hamas war in Gaza.

Burns is leading U.S. negotiations to resolve the conflict and address humanitarian issues.

On Friday, Ukrainian President Volodymyr Zelenskyy urged military allies to provide more weaponry to strengthen Ukraine’s defense as Russia continues its invasion.

Speaking at Germany’s Ramstein Airbase during the Ukraine Defense Contact Group (UDCG) meeting, Zelenskyy stressed the need for improved air defense systems and permission to use U.S.-supplied long-range weapons to target locations in Russia and Russian-occupied Ukrainian territory.

Zelenskyy highlighted the urgent need for additional air defense systems due to recent drone and missile attacks.

He noted that while some support has been provided, several promised systems have not yet arrived.

U.S. policy currently restricts Ukraine from using U.S. weapons to strike deep within Russia.

White House national security spokesperson John Kirby confirmed that the policy remains unchanged but noted that discussions with Ukrainian officials are ongoing.

Defense Secretary Lloyd Austin, speaking at the UDCG meeting, reiterated support for Ukraine’s immediate needs, including air defense and armor.

He also emphasized the importance of Ukraine boosting its own defense production for long-term security.

NATO Secretary-General Jens Stoltenberg, in a related development, called for continued military support for Ukraine, echoing Zelenskyy’s appeal.

He stressed that a strong Ukraine is crucial for ending the war and urged all allies to maintain their support during this critical period.

Some information for this report was provided by The Associated Press, Reuters and Agence France-Presse.