A group of U.S. ambassadors in South Korea, China, Japan and other Indo-Pacific countries has sent a letter to Congress, urging lawmakers to act quickly to pass legislation on assistance to Ukraine, Israel and others in the Pacific, a White House official said Tuesday.

John Kirby, the National Security Council coordinator for strategic communications, revealed the delivery of the letter written by nine U.S. ambassadors, underscoring the importance of the congressional passage of President Joe Biden's national security supplemental funding request.

"The ambassadors wrote about how many countries in the Indo-Pacific are intently focused on the conflicts in Ukraine (and) in the Middle East," Kirby said during an online press briefing.

"Russia's growing strategic partner(ship) with the People's Republic of China, military support from Iran and North Korea ... our support for Ukraine and the potential termination of that support at such a decisive moment here in these winter months will fundamentally affect not just Ukraine, but other strategic theaters as well, obviously, to include the Indo-Pacific theater," he added.

The letter came amid concerns that failure to pass the funding package for Ukraine, Israel and border security could raise questions over America's defense commitments to regional allies and partners

"The governments of US allies are watching what we are doing at this pivotal moment in history - a time when the decisions we make now will have long-term consequences for years to come," their letter noted.