NATO is critical to security of United States: Barack Obama

US President Barack Obama has said NATO is "critical" to the security of America and its allies in Europe, a virtual rejection of Republican front-runner Donald Trump's views that the intergovernmental military alliance has outlived its utility.

"NATO continues to be the linchpin, the cornerstone of our collective defence and US security policy," Obama told reporters on Monday along with NATO Secretary General Jens Stoltenberg in the White House. The Obama-Stoltenberg meeting came in the wake of Trump's remarks. White House Press Secretary Josh Earnest has termed such remarks as "ill-advised". Obama, however, did not make any direct comment on Trump's comments.

Obama said he had an excellent discussion that started with marking the tragedy that had taken place in Brussels, and reinforcing the importance of us staying focused on ISIS and countering the terrorism that has seeped up into Europe and around the world. "We agreed that one of the most important functions that NATO is performing and can continue to perform is to help in the training and assisting process for troops in Iraq, in Jordan, in many of the areas in the region.

"And we are continuing to cooperate on an ongoing basis about operations potentially in areas like Libya, where you have the beginnings of a government and we can I think provide enormous help in helping to stabilise those countries," Obama said.

Obama and Stoltenberg also discussed situation in Afghanistan, Russia and Ukraine. "We continue to be united in supporting Ukraine in the wake of Russian incursions into Ukrainian territory. We continue to work in a train-and-assist fashion in helping support Ukraine develop its military capabilities defensively," he said. Stoltenberg said NATO is as "important as ever".

"Because NATO has been able to adapt to a more dangerous world. We stand together in the fight against terrorism. Terrorism affects us all, from Brussels to San Bernardino, and all NATO allies contribute to the US-led efforts to degrade and destroy ISIL(Islamic State).

"And just last week, we started training Iraqi officers, and we will continue to support the efforts of the United States and other countries to fight ISIL ," he said. The US value the contributions it received from the large number of NATO members who are a part of counter-ISIL coalition, Earnest said.