The United States could grow a full percentage point less in 2012 should a European country default, according to U.S. investment bank Goldman Sachs.

While the U.S. economy is growing, its banking sector remains exposed to banks in Europe.

Should one or more of those countries default, it would send shockwaves through the banking sector across the continent and eventually over to the U.S. banks, making a lackluster recovery even more sluggish.

Specifically, Goldman Sachs finds, should eurozone banks cut their lending to the U.S. by 25 percent in event of a default, they would cut about 0.4 percentage points from growth directly, and slice it by a full percentage point after the effects trickle through the entire U.S. financial system, Goldman Sachs reports.

Translation: The U.S grows 1.5 percent in 2012 instead of 2.5 percent.

"A reduction in the lending of foreign banks to U.S. counterparties could have a meaningful impact on U.S. growth," Goldman chief economist Jan Hatzius writes in a research note, CNBC reports.

"While the numbers are not huge, it is important to note that the overall effect could be significantly larger if there are spillovers from the behavior of foreign banks to the behavior of domestic U.S. banks."

Other experts agree that counterparty risk poses a serious threat.

"You may not be holding any problem debt yourself, but your counterparty could be experiencing distress, and the relationship is no longer on firm footing," says John Jay, senior analyst at Aite Group, a financial research firm, according to the Huffington Post.

"If you're an American bank, and global in nature, undoubtedly you are dealing with someone who holds that sovereign risk."