Obama: Islamic State Fight Is 'No 1 Priority'

The President responds to criticism after the attacks in Belgium put national security back on top of the US political agenda.

President Barack Obama has said the fight against Islamic State is his "number one priority", as a top US lawmaker suggested Americans were probably targeted in Brussels.

The deadly terror attacks in Belgium have thrust national security back to the top of the US political agenda, with the President facing criticism from Republicans looking to replace him in November.

A day after IS claimed responsibility for the bombings, Mr Obama responded to questions about his strategy for fighting the extremist group.

The Brussels attacks prompted heightened security at US transportation hubs

"I think it is important to recognise that this is my number one priority," the President said at a news conference in Argentina.  

"There is no more important item on my agenda then going after them and defeating them."

Republican presidential candidates Donald Trump and Ted Cruz have been critical of Mr Obama, saying he needs to do more to keep Americans safe at home and abroad.

Following the attacks in Brussels, Mr Trump said he would bring back torture and "do a lot more than waterboarding", while Mr Cruz said he favoured patrolling and securing Muslim neighbourhoods "before they become radicalised".

The President on Wednesday noted the challenge of locating and identifying small groups of people willing to die in terror attacks, but said it was "un-American" to single out Muslim communities for more surveillance.

Meanwhile, a top US lawmaker has said the Brussels attackers may have attempted to target Americans, noting the blasts were close to US airline counters.

"From what I've been told, it was closer to American carriers," said Devin Nunes, chairman of the US House Intelligence Committee, who has been briefed on the bombings.

"It looks like it was targeted toward Americans to some degree."

State Department spokesman Mark Toner told CNN on Wednesday it appeared that about a dozen Americans were injured in the attacks.

He could not confirm whether any US citizens had been killed.

The attacks led to major US transportation hubs going on high alert. Airports in Atlanta and Denver have ordered evacuations over suspicious packages.

The US State Department issued a travel alert for all US citizens heading to Europe until 20 June.

Secretary of State John Kerry will travel to Brussels on Friday to meet with top Belgian and European officials.