The top leaders at the Pentagon said Friday that they do not believe Russian President Vladimir Putin has made a decision to attack Ukraine but he has amassed the capabilities to give him plenty of options. 

Defense Secretary Lloyd Austin and Chairman of the Joint Staff General Mark Milley on Friday urged Russia to take the diplomatic route instead of invade Ukraine. 

“There’s no reason that this situation has to devolve into conflict,” Austin said during a briefing with reporters. “He can choose to de-escalate. He can order his troops away. He can choose dialogue and diplomacy.” 

Milley told reporters that Russia has gathered upwards of 100,000 forces near Ukraine’s borders. He also listed the capabilities such as ground maneuver forces, ballistic missiles, air force and said civilians could suffer if war were to break out in the scale and scope possible. 

“You can imagine what that might look like in dense urban areas, along roads and so on and so forth. It would be horrific. It would be terrible. And it’s not necessary and we think a diplomatic outcome is the way to go here,” Milley said. 

Milley drew attention to the terrain of Ukraine, saying that it includes high water tables that when frozen are optimal for vehicle maneuvers. The conventional wisdom is that Russian forces will wait to launch an attack until the ground freezes so tanks can move easily. 

The Pentagon has put 8,500 U.S. troops in the U.S. on heightened alert for a possible deployment to Eastern Europe. 

The vast majority would deploy as a part of the NATO Response Force. iIf the alliance activates it to shore up the countries on the eastern flank of NATO. U.S. troops already in Europe could also move to the eastern flank of NATO if needed. Austin said Friday that no troops had moved.