They have serious credibility problems. First off, members of the mission are free to travel anywhere in Ukrainian controlled territory. Russia is a member of the OSCE and has people on the ground as part of the OSCE mission. It has not escaped notice that Ukrainian military positions are shelled rather accurately after OSCE visits.
Secondly, the OSCE is NOT allowed to travel in the Russian controlled areas except when and where the terrorists allow them. They have not seen any Russian troops or Russian equipment cross the border because they're not allowed to. OSCE can only monitor two border crossing sites along a 400 km frontier and of course nothing and no one crosses at those sites. They do see the new equipment in Luhansk and Donetsk which is obviously Russian and from Russia but unless they see it cross the border, their hands are tied.
They are getting a bit fed up with this. Their positions are increasingly dangerous as the war continues. They are trying to recruit 250 more people with military experience but the only applicants are Russian. How useful they are is questionable as Russia simply denies any reports that are not favourable to the terrorists. One hopes they give some credibility to Ukrainian reports in the rest of the world.
This gets to the subject of American and EU's policy towards the war in Ukraine which is a puzzle to many. Both are doing everything they can to help on the civil side of things - billions of dollars in loans and loan guarantees, advising on reforms and so forth. America, Canada, Australia and EU members are providing non-lethal aid to Ukraine, (delivered by volunteers to the Ukrainian forces so the still highly corrupt bureaucracy doesn't steal it and sell it on the black market). But NOBODY seems to be willing to sell weapons which we so desperately need. Obama has clearance from Congress, EU cleared individual members but even Poland hasn't done anything visible in the way of arms.
Part of the reason is that Russian continues to maintain that they're not supplying arms and troops to the terrorists in eastern Ukraine. Plausible deniability. "Prove it", they say. There is all kinds of proof they are here but none that they crossed the border from Russia, at least none that will be enough to back Putler and Lierov into a corner.
At Davos, Lavrov said that so far no one has shown him proof because either they can't OR THEY DON'T WANT TO (emphasis mine). Unless American spy satellites are as useless at tracking military movement as the NSA data collection is at preventing terrorist attacks around the world, America should be able to provide and accurate count of everything that crossed the Russian Ukrainian border. But they haven't released it and they won't. Lavrov knows it and is just rubbing it in.
If America did release the information, it would mean that people would know exactly what was going on and America could no longer pretend along with Russia. They would be expected to do something. The question is what? If the West begins to arm Ukraine there will be no "plausible deniabilty" and it will "prove to Putin" that NATO aka USA is out to destroy his country. (They really do believe their own press releases). At which point he can claim Russia is under attack by NATO and retaliate overtly with what ever armed forces he wishes. Which of course will destroy Ukraine with great loss of life.
UNLESS more countries are drawn into the war. At which point, since we are dealing with a mad man, it may well go nuclear. Kyiv. Warsaw. What will it take to draw American nuclear retaliation and we all go up in a cloud of radioactive dust?
It is pure and simple blackmail. Putin wants to sit down with a map in front of Merkel and Obama and secretly divide up the world, Molotov-Ribbentrop style, or back when everyone did it, Sykes-Picot style. Putin is still in the 19th century. The problem is he thinks everyone else is too.
Sanctions will not stop Putin, they simply reinforce his paranoia that nobody loves him; everybody hates him and is trying to destroy Russia. It is coming to war. Now or later. Take your pick. Arms for Ukraine would at least call his hand.
A couple of headlines: