US President Barack Obama and German Chancellor Angela Merkel hold a joint news conference following their meeting at the White House in Washington February 9, 2015. [Photo/Agencies]

WASHINGTON/DONETSK, Ukraine - US President Barack Obama signaled on Monday he will wait for the results of high-stakes talks on Ukraine before deciding whether to arm the Kiev government, saying diplomacy and sanctions remain his preferred tools to resolve the crisis.

Obama, at a White House news conference with visiting German Chancellor Angela Merkel, said providing weapons to Ukraine was among the options he and his advisors were considering.

But he made clear he had reservations about upping the ante in Ukraine and endangering US-European unity in the contest of wills with Russian President Vladimir Putin. Merkel opposes sending weapons to Kiev to help it fight pro-Russia separatists.

"It is true that if, in fact, diplomacy fails, what I've asked my team to do is to look at all options," Obama said. "But I have not made a decision about that yet."

In the face of a new offensive by separatists in eastern Ukraine, some of Obama's top advisors, as well as hawkish US lawmakers, are pressing him to do more to help the Ukrainian government defend itself.

But that question has been overshadowed, at least temporarily, by a revived diplomatic push led by Merkel and French President Francois Hollande. The two are due to meet with Putin and Ukrainian President Petro Poroshenko in Belarus on Wednesday.