What are Russia's options beyond full Ukraine attack?

Russian President Vladimir Putin appears to be preparing to launch an invasion of Ukraine, with more than 100,000 troops positioned around the country. Certainly, the U.S. believes that's the case and U.S. President Joe Biden has warned Ukrainian President Volodymyr Zelenskyy that an attack could come in February.

But Russia denies it's preparing to invade and Putin's intentions remain a mystery.

Russia, which is seeking a pledge that NATO won't expand to include Ukraine, has options it could pursue short of a full-blown invasion, and other ways to lash out at the U.S. and its allies. All of them carry varying degrees of risk, to Russia and the world.

A look at some of them:

In 2014, Russia seized the Crimean Peninsula from Ukraine. That year it also started arming rebels in the eastern region known as the Donbas, starting a low-boiling conflict that has killed more than 14,000 people. Many Russia watchers speculate that the recent buildup of Russian troops and naval forces is the next chapter in a larger effort to chip away at Ukraine, perhaps taking advantage as the U.S. and its allies in Europe are distracted by COVID-19 and other issues. Possible scenarios include providing additional support to the Russia-backed rebels or launching a limited invasion, just enough to destabilize Zelenskyy and usher in a pro-Kremlin leader.