DONETSK, Ukraine (CNN) - International investigators' quest to carry out their duties at the crash site of the downed Malaysian airliner hit another roadblock Wednesday, as Ukrainian officials warned of possible land mines near the site.
Ukraine's National Security and Defense Council claims that "terrorists" -- the term it uses to describe rebels -- have set up firing positions and laid mines on the access road to the crash site of Malaysia Airlines Flight 17.
The Ukrainian government and pro-Russian rebels are fighting over control of eastern Ukraine.
Dutch investigators in Ukraine did not mention mines but announced Wednesday that unsafe conditions kept their contingent from visiting the crash site for the fourth straight day.
CNN could not independently confirm the veracity of the statement by the Ukrainian officials, though CNN's Nick Paton Walsh traveled to and from the debris field safely Wednesday.
The dangers in the area make the work of international experts "impossible," the Ukrainian defense council said.
Workers with the Organization for Security and Co-operation in Europe made the same call and avoided traveling to the crash site Wednesday.
Ertrugrul Apakan, chief monitor of the OSCE Special Monitoring Mission to Ukraine, said he would like to see a cease-fire between combatants so investigators can work.
It was the fourth straight day the OSCE has joined the 50-strong team of Dutch and Australian investigators in declaring the region too dangerous to work in.
Dutch investigators have yet to lay eyes on the wreckage or the human remains believed still to be strewn across the huge debris field near the town of Torez.
CNN's Walsh was there and reported seeing three or four points of smoke from artillery fire. Because the area was militarized before the plane crash, it was not possible to know whether those firing positions were new.
On the journey to the crash site, the CNN team saw only a small rebel presence on the road around the wreckage. The militants were "reasonably welcoming," Walsh said, noting that his team was traveling in only one car, as opposed to the convoy of dozens of vehicles that the investigators use.
At the crash site, Walsh reported seeing the cockpit of the aircraft with what appeared to be holes from shrapnel. Some human remains could still be found, as well as belongings from the victims scattered about.
U.S. and Ukrainian officials have said that a Russian-made missile system was used to shoot down MH17 from rebel territory on July 17. Russia and the rebels have disputed the allegations and blamed Ukraine for the crash.
Dutch Prime Minister Mark Rutte asked Ukrainian President Petro Poroshenko in a phone call Tuesday morning to halt the fighting around the crash site so that investigators can access it, Rutte spokesman Jean Fransman said.
There are echoes of the Cold War as pro-Russian rebels battle Ukrainian government forces in the nation's east.
With new sanctions announced by the European Union and United States against Russia this week, the stakes are getting higher, and Moscow is getting more isolated.
The Russian Foreign Ministry said the latest round of U.S. sanctions "will cause nothing but the harm" to U.S.-Russian ties and "will create a poor environment in international affairs where the cooperation between our countries often plays a key role."
A day earlier, U.S. President Barack Obama said that the new sanctions "will continue to ratchet up the pressure on Russia, including the cronies and companies supporting Russia's illegal activities in the Ukraine."
"In other words, today, Russia is once again isolating itself from the international community, setting back decades of genuine progress," Obama said.
The Russian response accused the United States of "trying to avoid responsibility" for the crisis in Ukraine and blamed the Ukrainian government for the violence in the east.
The new and harder-hitting sanctions show the West's waning patience with Russia over its disputed annexation of Crimea, its support of pro-Russian rebels and the impact of the shoot-down of Flight 17, which had many Europeans among the 298 people on board when it went down in eastern Ukraine.
Some of the new EU sanctions target eight "cronies" of Putin and three "entities" by limiting their access to EU capital markets, an EU official said on condition of anonymity. The people and entities will be named Wednesday, the official said.
Three state-owned banks were named Tuesday by Washington, meaning five of the top six financial institutions in Russia were on the sanctions list, according to a senior Obama administration official.
Furthermore, the United States went to NATO with a claim that Russia has violated its obligations under the Intermediate-Range Nuclear Forces Treaty. The treaty prohibits that possession, production or flight-test of a ground-launched cruise missile with a range of 500 to 5,500 kilometers. In a statement, NATO asked Russia to resolve the issue.
A parental quest
Although heavy fighting has blocked investigators from getting to the crash site, it didn't stop the determined parents of one of the victims.
George and Angela Dyczynski braved the regional conflict and saw the wreckage over the weekend.
"We have been always protected," George Dyczynski said. "I believe it was divine guidance."
"We really, really promised our daughter that we will go there and that we tried to really fulfill our promises," said Angela Dyczynski.
Despite there being no known survivors, the couple holds out hope that their daughter, Fatima, a 25-year-old aerospace engineer, is still alive.
"Fatima can only be pronounced dead when the DNA is matched with her body," Angela Dyczynski said. "So if anybody says at the moment she is dead ... it's not correct."
Up to this point, very few of the bodies recovered from the crash have been identified by Dutch authorities.
As of Monday, 227 coffins had been sent to the Netherlands, where forensic investigators are working to identify victims. It is unclear how many complete sets of bodies the coffins contain.
Reports of ballistic missiles
The United States and others say Russia has provided arms to rebels in eastern Ukraine, including heavy weapons such as a missile system like the one believed to have been used to down the Malaysian airliner 12 days ago.
Despite previous sanctions, the flow of weapons continues and on Tuesday the fighting entered a dangerous new phase.
A senior official within the Ukrainian counterterrorist unit told CNN on Wednesday that Tochka-U ballistic missiles were fired Tuesday toward the Saur-Mohyla area of eastern Ukraine, a strategic hill that has been the scene of fierce fighting for the past week. The Ukrainian military claimed to have captured the hill on Monday.
It's the same area where pro-Russian rebels shot down two Ukrainian warplanes last week.
Three U.S. officials told CNN on Tuesday of reports that Ukraine's government had used short-range ballistic missiles against the rebels over the previous two days.
The weapons have a range of about 50 miles (80 kilometers) and pack up to 1,000-pound (454-kilogram) warheads. If the reports are accurate, they are the most deadly missiles used in the conflict to date.
The U.S. officials did not specify where the missiles hit or what damage they caused.
One U.S. official said there has been no reaction from Russia.
Another of the U.S. officials said that using the missiles is "an escalation, but Ukraine has a right to defend itself."
Ukrainian Foreign Minister Pavlo Klimkin acknowledged that his country's military has short-range missiles, but denied that the military fired any.
In a joint news conference with Klimkin, U.S. Secretary of State John Kerry praised Ukrainian officials for proposing a peace plan that includes "serious and substantive dialogue with the Russian-backed separatists."
Is the Cold War back?
On Wednesday, Russian lawmaker Aleksey Pushkov, the head of the State Duma's foreign affairs committee, said via Twitter that Obama "will make history not as a peacekeeper, everyone forgot about his Nobel Prize, but as the statesman who started a new cold war."
Despite the escalating tensions and the new sanctions, Obama said this is not part of a new Cold War.
"What it is is a very specific issue related to Russia's unwillingness to recognize that Ukraine can chart its own path," Obama said.
One of the senior administration officials said Russia hasn't been this isolated "since the end of the Cold War."
Obama said Russia could choose a different path.
"It didn't have to come to this. It does not have to be this way," Obama said. "This is a choice that Russia and President Putin in particular has made. ... The path for a peaceful resolution to this crisis involves recognizing the sovereignty, the territorial integrity and the independence of the Ukrainian people."