''We have the greatest security crisis in Europe since the Cold War,'' she affirmed in an interview with public broadcaster TVP.
''To disregard this would be irresponsible,'' she added.
''Yet sending signals that spark anxiety among our citizens would also be too much.
''So we need to have a balanced position,'' she said.
Kopacz claimed that Poland's membership of NATO is the country's guarantee of security. To date, Poland has been one of the most vigorous defenders of the new Kiev government.
''We need to protect our own interests, but at the same time to fight for something that Ukraine is fighting for today.
''For the first time, blood is actually being shed for the European Union, or for an attempt at integration into the European Union.''
Russian tanks crossing Ukrainian border?
Meanwhile, the US State Department claimed on Tuesday that Russian tanks and military equipment have been crossing the Ukrainian border in recent days, in violation of the ceasefire agreed in Minsk on 12 February.
U.S. Assistant Secretary of State for Europe, Victoria Nuland, told the Senate Foreign Relations Committee that besides tanks, pro-Russian separatists have received armoured vehicles, heavy artillery and rocket equipment.
She noted that the White House is still considering arming Ukraine.
On Monday, European Council President Donald Tusk and US President Barack Obama said that current sanctions against Russia will be maintained. Additional sanctions are pending, depending on the ceasefire.
"In the coming days, days not weeks, we need to see a complete ceasefire," Nuland said.
"Pressure is going to have to increase if Minsk is not implemented." (nh)