For the first 9 minutes of the period, US players took advantage of every opportunity to hit the Czechs. Ryan Callahan was playing especially physically, as this tweet described very well...
Ryan Callahan is hitting quite literally everything. If the kid eating ice cream in the front row had the puck, Callahan would drill him.
— Chris Peters (@chrismpeters) February 19, 2014
The US got a power play shortly after Callahan's rampage, and you just got the feeling after all those physical wins, they'd find a way to score. And that's what happened. Zach Parise scored a goal that was both finesse and toughness. The finesse was the coordination and hands required to score, the toughness was that he scored from close range, in one of the so-called "dirty areas" of the ice.
All 4 US goals have been scored in those tight areas near the net, and the US has dominated that part of the ice in both periods so far.
So Team USA is 20 minutes away from qualifying for the semifinals and playing the winner of Latvia/Canada (which is tied 1-1 as I'm writing this).
However, you can't run out the clock in hockey. There's no such thing as a prevent defense in this game. The US needs to continue to do what they did in the first two periods: Make the Czechs work for everything. Make them pay a price for every pass. Be aggressive but be smart. Don't give them any power play chances (like Brooks Orpik did with his late hit on Jaromir Jagr. Good God I hate Orpik).
Be patient. The opportunities to hit and the opportunities to score will come.