Alexander S. Vindman and his twin brother, Yevgeny, were three years old when they fled Ukraine with their father and grandmother, Jewish refugees arriving in New York with only their suitcases and $750.

In the 40 years since, he has become a scholar, diplomat, decorated lieutenant colonel in the US army and Harvard-educated Ukraine expert on the White House National Security Council.

Colonel Vindman’s testimony will offer a compelling immigrants’ tale and a glimpse into the story of twin brothers who have lived a singular American experience. From their days as little boys in matching short pants and blue caps, toddling around the Brighton Beach neighbourhood of Brooklyn — known as Little Odessa for its population of refugees from the former Soviet Union — and into adulthood, they have followed strikingly similar paths.

Like Alexander Vindman, 44, Yevgeny is a lieutenant colonel in the US army. He also serves on Donald Trump’s National Security Council, as a lawyer handling ethics issues.

When Alexander Vindman decided to alert a White House lawyer to his concerns about Trump’s July telephone call with the Ukrainian President, he turned to his twin, bringing him along as he reported the conversation to John A. Eisenberg, the top National Security Council lawyer.

The twins both married, and they have offices across from one another in the West Wing of the White House, according to Carol Kitman, a photographer who met the family when they were boys, chronicled their growing up and remains a close family friend.

“They say nothing,” Kitman said, when asked if the two had revealed their views about Trump. “They’re very smart and they’re very discreet.”

Along with their older brother, Leonid, the twins left Kiev with their father shortly after their mother died there. Their maternal grandmother came along to help care for them. The family sold its possessions to survive in Europe while waiting for visas to the US.

“I think their father felt they would do better in the United States as Jews,” said Kitman, who recalls spotting the grandmother and the two boys, then known as Sanya and Genya, under the elevated train in Brooklyn.

“Upon arriving in New York City in 1979, my father worked multiple jobs to support us, all the while learning English at night,” Colonel Vindman plans to tell House lawmakers on Tuesday. “He stressed to us the importance of fully integrating into our adopted country. For many years, life was quite difficult. In spite of our challenging beginnings, my family worked to build its own American dream.”

The twins’ father went on to become an engineer, Kitman said, and the twins’ older brother entered the Reserve Officers’ Training Corps in college.

In 1998, Alexander Vindman graduated from the State University of New York at Binghamton. He received his military commission from Cornell University, completed basic training at Fort Benning, Georgia, in 1999, and deployed to South Korea, where he led infantry and anti-armour platoons, the following year.

In his testimony, the colonel plans to mention his “multiple overseas tours”, including a 2003 combat deployment to Iraq that left him wounded by a roadside bomb, for which he was awarded a Purple Heart.

Since 2008, he has been an army foreign area officer — an expert in political-military operations — specialising in Eurasia. Colonel Vindman has a master’s degree from Harvard in Russian, Eastern Europe and Central Asian Studies.