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 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.

Also read: Austin says Putin now has full range of options in Ukraine

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:

Something short of a full-scale invasion

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.

Also read: Russia says US ignored its security demands over Ukraine

Stopping short of a full-scale invasion would give Russia more time to get more forces in place and test the commitment of the U.S. and its allies to the punishing sanctions promised by Biden, says retired Lt. Gen. Ben Hodges, former commander of U.S. Army forces in Europe. “He’s going to continue doing what he’s doing right now, continuing to apply maximum pressure on Ukraine and to try to destabilize the government to alarm people,” Hodges said. “There’s a lot of capability in place to do more, should the opportunity present itself.”

Also read: Amidst rising tensions in Ukraine, Russia assures to not start a war

That might still end up triggering sanctions that could damage the Russian economy and hurt Putin at home. There’s also the risk that a limited action isn’t enough to achieve the Russian president’s goal of undermining European security by rolling back, or at least halting, NATO expansion, says Dmitry Gorenburg, an analyst with CNA, a research organization in Arlington, Virginia. “I don’t think it gets him what he wants,” he said. “It didn’t get them that before. So why now?”

Also read: United States tries to name and shame Russian disinformation on Ukraine

Economic warfare

Russia is a major player in global energy, the third-largest oil producer after the U.S. and Saudi Arabia, and the source of about 40% of the natural gas used in Europe. It is also a major exporter of wheat, particularly to developing nations. Any move to cut the flow of energy could be painful to Europe in winter with gas and oil prices already high. Similarly, rising food prices are a problem around the world.

Also read: US President Joe Biden says Russian invasion in February ‘distinct possibility’

Putin has some economic leverage, but there’s no indication he would use it and it could end up hurting Russia in the long run, says Edward Fishman, a former State Department official who is now a senior fellow at the Atlantic Council’s Eurasia Center. Any move by Russia to cut off gas shipments would push European nations to find alternative sources for the future. “It’s a weapon you can only use once,” he said. “You do that once and you lose that leverage forever.” The Biden administration is already working with Qatar and other suppliers to replace Russian gas if needed.

Also read: Ukraine crisis: What to know as tensions rise

Cyberattacks

There’s no doubt Russia has the capability to conduct significant cyberattacks in Ukraine and around the world, and would almost certainly do so again as part of any operation against its neighbor. The Department of Homeland Security warned law enforcement agencies on Jan. 23 that Russia would consider initiating a cyberattack on the U.S., including possible actions against critical infrastructure, if it perceived the response to an invasion of Ukraine “threatened its long-term national security.”

Also read: Germany, US threaten to halt Nord 2 Stream gas pipeline if Russia invades Ukraine

Russia is the suspected culprit in a 2015 hack against the Ukraine power grid. Hackers this month temporarily shut down government websites in Ukraine, underscoring how cybersecurity remains a pivotal concern in the standoff with Russia. “Whatever the size and scale and nature of their ground and air attacks, cyber will be a big part of anything they do,” warns Hodges.

Also read: Joe Biden and Kamala Harris should resign: Ex-ambassador Nikki Haley

The risk to the world is that hostile activity against Ukraine could spread, as the cyberattack known as notPetya did to devastating effect in 2017. The downside to Russia is the U.S. and other nations have the power to retaliate, as Biden warned Putin in June. “He knows there are consequences,” Biden said.