WARSAW, Poland - Polish President Bronislaw Komorowski stood next to Vice President Biden today as he tweaked the U.S. for not doing more to counter Russia's military buildup, but Biden - looking directly at Komorowski - tweaked right back.

Komorowski, who received Biden at his presidential palace, said that Russia had for years been able to beef up its military spending with impunity, allowing Russian President Vladimir Putin to turn his armed forces into "an instrument of external policy," the Polish president said. Komorowski said it should come as no surprise that Russia was so aggressive with the Ukrainian region of Crimea.

Vice President Biden, left, talks to Polish President Bronislaw Komorowski, right, during a meeting in Warsaw, Poland on March 18, 2013. Janek Skarzynski/AFP/Getty Images

"We have to take these simple data about the gigantic increase of the level of funding of the Russian armed forces as a challenge as well as a lesson to be learned for the future of the whole NATO," Komorowski said.

It was then Biden's turn to speak at the two leaders' joint press availability and he appeared to take issue with Komorowski's suggestion that the United States had not done enough to counter Russia's influence.

"Russia has increased their budget," Biden said. "But I want to remind you that you have an ally whose budget is larger than the next 10 nations combined. So while others may not have stood up to their responsibilities, the United States has more than stood up to its responsibilities," he said, looking directly at Komorowski.

"So," Biden continued, "don't worry about where we are."

Poland is one of the few NATO countries that has increased its military spending in recent years.