WASHINGTON–The Russian takeover of Crimea has transformed the security situation in the Black Sea for NATO ships and aircraft, the head of the US European Command and allied commander of NATO said on Wednesday.

"Crimea has been transformed in some fairly significant ways as far as weapon systems" Gen. Philip Breedlove told reporters in the Pentagon briefing room. "And these weapon systems, from air defense systems that reach nearly half of the Black Sea to surface attack systems that reach almost all the Black Sea area have made the platform of Crimea a great platform for power projection into this area."

Breedlove made his comments on a day when US and Russian forces made force demonstrations just miles apart on opposite sides of the Estonian border.

Elements of the US Army's Second Cavalry Regiment drove Stryker vehicles through the streets of Nava, Estonia, as part of a military parade to mark Estonia's Independence Day in the town on the Russian border, while at the same time 2,000 Russian paratroopers conducted exercises just over the border.

The American unit is in Estonia for a series of training exercises with the Estonian military.

NATO has stepped up its presence in Eastern Europe in recent months to assuage its allies close up against the Russian border, which are nervously looking at the Russian incursions into Ukraine.

Testifying before the House Armed Services Committee, Breedlove said that "in the current configuration I do not think that Ukrainian forces can stop a Russian advance in Eastern Ukraine…and to the degree that we can supply help, I'm not sure that they could stop a Russian advance in Eastern Ukraine even if we supply aid."

He refused to say that he supported arming Ukrainian forces with lethal weapons, but admitted on the Hill that "what we're doing now is not changing the results on the ground."

At the Pentagon, Breedlove said that Moscow has sent "more than 1,000 pieces of Russian military equipment" to Ukrainian separatists and Russian forces fighting in Ukraine, "including tanks, armored personnel carriers, heavy artillery pieces and other military vehicles and equipment."

And still, "it could get worse" he said.

On Feb. 26, the Ukrainian government began pulling heavy artillery pieces off of the front line as part of the ceasefire agreement forged earlier this month between the Kiev government and pro-Russian separatists in the eats who are being supplied by Moscow and bolstered by Russian troops.

While declining to state whether or not he favors arming the Ukrainian forces with more lethal weaponry, Breedlove said that he was convinced the US and NATO need to continue to develop plans to coordinate more effective diplomatic, military and economic tactics to blunt Russian president Putin's ambitions in the region.

"We don't want a war of grand proportions in Ukraine" he said. "We must find a diplomatic and political solution. What is clear is that this is not getting better" with the present strategy.

US Army soldiers will deploy to western Ukraine soon to being training local forces, and Washington has also started to provide heavier military equipment to the government in Kiev as well. In January, the US delivered the first prototype of an armored "Kozak" vehicle for use with the Ukrainian border guard, according to the US Embassy there.

A posting on a US government contracting site put the cost of the vehicle at $189,000.

The vehicle is built on a chassis manufactured by Italian company Iveco and features a V-shaped armored hull to help protect against mines and roadside bombs. The embassy said that to date, "the United States has delivered dozens of armored pickup trucks and vans to the Ukrainian Border Guard Service. The Kozak is larger and offers a higher level of protection."