"I was recently in Kiev myself, about a month ago, and when you are there however briefly you cannot help but be struck by the intensity of this issue for the Ukrainians," Clapper said on Monday, answering a question about whether the United States should arm Kiev's army.
Earlier this week, at the Council on Foreign Relations, a New York think tank, Clapper argued providing lethal "defensive" weapons to the Ukrainian government troops would "bolster their morale" in the military confrontation against eastern independence supporters.
In December, US Congress authorized the allocation of $350 million to arm Kiev. However, US President Barack Obama has not enacted the legislation.
Kiev and the independence supporters signed a ceasefire deal last month, yet both sides reported numerous violations of the truce. The conflict in eastern Ukraine has claimed more than 6,000 lives, according to the UN.