As history books defined it, the Cold War started after World War II. It involved the U.S. and its allies versus the Soviet Union and its allies.
The rivalry was political, economic, ideologic, but it stopped short of an outright military conflict.
Now, though, there's a military buildup in Eastern Europe that's the largest since the Cold War. The United Kingdom is planning to send fighter jets to Romania. The U.S. is set to send troops and tanks to Poland. Russia recently sailed warships close to British waters on their way to Syria.
It all has international officials asking, is this the beginning of a new Cold War?
MATTHEW CHANCE, CNN SENIOR INTERNATIONAL CORRESPONDENT: Well, not since the end of the Cold War have tensions between Russia and the West been this high.
SUBTITLE: The new Cold War?
CHANCE: The big flashpoint is, of course, Syria. Russia's bombing in support of its ally, the Syrian president, has drawn condemnation from the United States and Europe. Russia has responded by bolstering its military in Syria, deploying even more state of the art anti-aircraft missiles, and by upping its rhetoric.
Of course, the Syria conflict is only one of the flashpoints between Russia and the West. Another is Ukraine, where Russia is under Western sanctions for fueling of bloody rebellion in the east of the country after annexing Crimea in 2014.
There's also the issue of hacking, with Russia accused by U.S. officials of breaking into computer systems of political institutions. The Kremlin denies it, but there is a growing sense that Russian and the West are locked in a collusion course over a whole range of issues. But it's argued that Russia's president, Vladimir Putin, is just an autocrat bent on subverting the international order to which Russia was invited to be a part.
But I think many Russians see it differently. They see a world that after the end of the Cold War was almost totally dominated by the West and by United States in particular.
RONALD REAGAN, FORMER U.S. PRESIDENT: It's our duty to speak in this place of freedom.
CHANCE: Russian interests and concerns, they believe, have been trampled on with NATO expansion and the toppling of former Russian allies in the Balkans and in the Middle East. And what many Russians like about Putin is that he is saying enough is enough and standing up to U.S. dominance.
PRES. VLADIMIR PUTIN, RUSSIA (translated): We need to strengthen the security and defense capability of our country, to assert its position on the international stage.
CHANCE: So, what Syria and Ukraine and hacking are really about is this: like it or not, that relationship between Russia and the West, after the Cold War, the post-Cold War settlements, as it's sometimes called, is now being renegotiated.