Washington (CNN) Angela Merkel, the German chancellor desperately working to reach a diplomatic accord ending unrest in eastern Ukraine, continued her efforts at the White House Monday, urging President Barack Obama to forestall sending lethal aid to Kiev.

Her efforts appeared effective; at a midday press conference, Obama said he hadn't yet decided whether or not to send arms and equipment to besieged Ukrainian troops in the eastern part of the country.

But both leaders hinted there could be disagreements to come on how to best end the unrest that has waged for months and so far claimed 5,000 lives. Obama left open the possibility of equipping Ukrainians with American weapons if Merkel's latest attempt at brokering a diplomatic end to the violence fails.

"There may be some areas where there tactical disagreements," Obama said. "There may not be. But the broad principle that we have to stand up for, not just Ukraine, but the principle of territorial integrity and sovereignty is one where we are completely unified."

Merkel used similar language, saying through a translator the alliance between the United States and Europe will continue to stand, will continue to be solid, even though on certain issues we may not always agree."

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