NATO summit launches in Warsaw with a tribute to all soldiers in NATO member states, including those fallen in the line of duty.
U.S. President Barack Obama took advantage of his visit to Warsaw to voice concerns about a controversial new law allowing the Polish government to appoint the judges of its choosing to the country's constitutional court.
Critics say the changes undermine democratic standards and are part of the government's broader effort to seize more control over state institution.
Obama told reporters in Warsaw he had raised the issue with Polish President Andrzej Duda on the sidelines of the NATO summit.
"I insisted that we are very respectful of Poland's sovereignty and I recognize that parliament is working on legislation to take some important steps, but more work needs to be done," he said.
The European Commission has already given Poland an official warning and said the country faced sanctions unless it repealed the law.
Heads of state are arriving at the venue for the Warsaw summit. British Prime Minister David Cameron said that his country, while it may leave the EU, will not turn its back on European defense.
Signing the joint declaration, European Council President Donald Tusk said “the EU and NATO face the same threats.”
He said the the EU and NATO will deepen cooperation to counter both physical and hybrid attacks.
“Our critical infrastructure could be attacked, our banking system could be hacked, or our citizens could be exposed to disinformation campaigns,” Tusk warned.
New NATO-EU declaration calls for the use of "all ways and means available" to address "challenges emanating from the south and East."
U.S. President Barack Obama pledged support for Ukraine and for continued sanctions on Russia.
"We'll continue to support Ukraine as it continues to undertake important political and economic reforms," he said in Warsaw. "The EU and the US are united in our commitment to maintaining sanctions on Russia until they fully implement its obligations under the Minks agreement."