Obama refused to give Russia a 'red line' with Ukraine

President Barack Obama warned on Monday that the US could give lethal weapons to help Ukraine fight against Russian-backed separatists.

But, speaking at a press conference with German Chancellor Angela Merkel, Obama wouldn't say at what point he would do so.

"There's not going to be any specific point at which I say, 'Ah, clearly lethal defensive weapons would be appropriate here,'" Obama said after a reporter asked if he had a "red line" for Ukraine. "It is our ongoing analysis of what we can do to dissuade Russia from encroaching further and further on Ukrainian territory."

Obama once infamously warned Syria's autocratic leader Bashar Assad that using chemical weapons against his country's population would be a "red line for us" and prompt a US military response.

"We have been very clear to the Assad regime, but also to other players on the ground, that a red line for us is we start seeing a whole bunch of chemical weapons moving around or being utilized," Obama said on August 20, 2012. "That would change my calculus."

According to former CIA Director Leon Panetta, the warning was "damaging" to US credibility when America did not follow up on its vow after Syrian forces dropped sarin nerve gas on the suburbs of Damascus in August 2013, killing 1,400 civilians.

"This was the real turning point for the administration's foreign policy," a former senior Obama adviser told US historian and Foreign Policy Group CEO David Rothkopf. "This was when things really started to go bad."

Robert Caruso, who served in the Bush and Obama administrations in the Pentagon and the State Department and sits on the Board of Trustees of The Eastern Project, told Business Insider that Obama's failure to offer a clear red line with Ukraine was also a "dangerous" mistake.

"President's Obama's remarks today regarding both Russia and Iran were extremely dangerous, When specifically asked what his red line is with regards to Russian aggression, Obama did not articulate one," Caruso said, also referring to Obama's vague statement about US negotiations with Iran to curb its nuclear ambitions. "America and NATO cannot afford to cede Ukraine to Russia and also cannot tolerate a nuclear armed Iran exporting terror around the globe. We saw what happened when Obama refused to draw a red line on Syria. Do we want to take that chance again?"

Merkel and other European leaders oppose arming Ukraine, partly out of fear of a proxy war with Russia. Ukraine has been at the center of an international crisis since last year, when Russia forcibly annexed Crimea and boosted Eastern Ukrainian separatists with military assistance. However, Obama played down their differences Monday and insisted they were focusing on economic and diplomatic pressure.

"Both Angela and I have emphasized that the prospect for a military solution to this problem has always been low. Russia obviously has a extraordinarily powerful military," the president said, touting US and European economic sanctions against Russia. "But what we have said is that the international community, working together, can ratchet up the costs."

Michael B. Kelley contributed to this report.