WASHINGTON — Republicans made a point of emphasizing during the impeachment hearings that President Donald Trump provided sophisticated weapons to Ukraine to deter Russian aggression, in contrast to the Obama administration, which declined to do so.

President Obama's decision was portrayed as an example of his timidity in foreign policy. But the story is more complicated than that, said former CIA Director John Brennan.

In particular, said Brennan, now an NBC News analyst, the military was opposed to providing Javelin anti-tank missiles to the Ukrainians during the Obama administration "because of fear that the Russians would get access to Javelin's sensitive technology," he said.

"The Russians had deep penetrations of Ukrainian intelligence, security, and military forces in the aftermath" of that country's 2014 revolution that overthrew a pro-Russian government he said, "and it took time to rid those forces of Russian moles, agents, and spies. That was the purpose of my visit to Kiev less than eight weeks after the Revolution of Dignity."

A robust debate ensued within the Obama administration about the provision of lethal aid, he said, and there were some who argued it would escalate the situation and provoke Russia. That's how Russian expert Fiona Hill described the Obama administration's thinking in her testimony.

"Some [officials] argued strenuously to provide lethal assistance, but the ultimate decision made by [Obama] was to provide only non-lethal military and economic assistance," Brennan said. "It was a tough decision. The Javelin issue is being misrepresented as a simple decision devoid of other considerations, and that was not the case."

Brennan points out that the Javelins are currently "under lock and key in Ukrainian rear areas, not on the front lines. Their presence in Ukraine, however, does send a strong deterrent signal to Moscow, which is good."

He added, "I believe it is appropriate that Ukrainian forces have Javelins now because of the work that has been done over the past five years to reduce Russian presence and influence, but giving Javelins to the Ukrainians earlier would have risked compromising a very important and sensitive weapon system that could have come back to haunt U.S. forces on the battlefield."