Aleksander Szczyglo, defense minister in Poland's previous government, went so far as to call today's signing one of three significant "milestones" since Poland regained full independence in 1989.
"First was NATO membership, then joining the European Union and now a tangible tightening of our alliance with the U.S.," he said.
Russia's renewed assertiveness and its invasion of Georgia has fortified fears that the Kremlin may attempt to regain its spheres of influence and meddle in Polish affairs.
"Russia wants to regain influence over Poland, similar to influence Russia enjoyed during the time of the Warsaw Pact," military analyst Michal Fiszer told ABC News. "Any increase in Polish defense and security goes against those plans."
It would seem that as a member of NATO and the European Union Poland should feel it has enough security guarantees. But many Polish politicians express frustration with Western Europe's approach to Russia as too submissive and vulnerable to Russian oil and gas blackmail.
Only weeks ago, the 18 months of Polish-U.S. missile talks appeared on the verge of collapse. The Poles suspended negotiations after the United States refused to meet their demands and public opinion polls found that 70 percent of Poles were against the missile shield on their territory. Poles began protesting the plan.
All that changed on Aug. 8, when Russian armor rolled into Georgia.
"When Russia performs military operations that are perceived as aggressive and brutal, even relatively far from our borders, people in Poland fear," political analyst Grzegorz Kostrzewa-Zorbas told ABC News.
"The war in Georgia very quickly and suddenly changed the mood of Poles," Kostrzewa-Zorbas said. "In a week, a strong majority emerged supporting the American missile shield in Poland."
Now, 63 percent support American military presence on Polish soil and feel that the closer ties enhance Poland's security.
The American side also had a large shift in opinion.
"The Americans were unwilling to give Poland any anti-missile and air defense system optimized to defend Polish airspace and territory. They did not want to give Poland Patriot missiles," he said. "Now it is different."
Pawel Zaleski, a member of the Polish parliament, told ABC News that it is clear that Russia is trying to "create an area of domination around its borders."
"People in Poland do remember history, and they understand what it means to have such a neighbor returning to his old ways," Zaleski said. "People see the war in Georgia ... so of course it creates an impact on people's thinking."
Marek Ostrowsk, an analyst for the Polityka weekly, told ABC News that Poland traditionally has more confidence in the United States than its European alliances.
"Traditionally and historically, we think America is more reliable than Europe," Ostrowsk said. "In 1918, we regained independence thanks to the U.S. When World War II began in 1939, we were let down by our allies, Britain and France. But the U.S. has never failed us."
ABC News' Michael S. James contributed to this report.